diff --git a/lib/ice-coder.js b/lib/ice-coder.js
index 8f4be48..f2f35a7 100644
--- a/lib/ice-coder.js
+++ b/lib/ice-coder.js
@@ -51,11 +51,14 @@ var ICEcoder = {
 	bugFilesSizesActual:	[],		// Array of actual sizes of bug files
 	githubDiff:		false,		// Toggle for viewing GitHub/FM diff view
 	githubAuthTokenSet:	false,		// Has the user set their GitHub token yet
+	splitPane:		false,		// Single or split pane editing
+	debounce:		"",		// Contains debounce timeout object
+	editorFocusInstance:	"",		// Name of editor instance that has focus
 	ready:			false,		// Indicates if ICEcoder is ready for action
 
 	// Set our aliases
 	initAliases: function() {
-		var aliasArray = ["header","files", "fileOptions", "optionsFile", "optionsEdit", "optionsRemote", "optionsHelp", "filesFrame","editor","tabsBar","findBar","content","footer","nestValid","nestDisplay","charDisplay","byteDisplay"];
+		var aliasArray = ["header","files", "fileOptions", "optionsFile", "optionsEdit", "optionsRemote", "optionsHelp", "filesFrame","editor","tabsBar","findBar","content","footer","nestValid","nestDisplay","splitPaneControls","charDisplay","byteDisplay"];
 
 		// Create our ID aliases
 		for (var i=0;i<aliasArray.length;i++) {
@@ -109,6 +112,7 @@ var ICEcoder = {
 		this.filesFrame.style.height = (winH-headerH-fileNavH) + "px";
 		this.nestValid.style.left = (this.filesW+10) + "px";
 		this.nestDisplay.style.left = (this.filesW+17) + "px";
+		this.splitPaneControls.style.left = (parseInt((winW-this.filesW)/2,10)-25-4+this.filesW) + "px";
 		top.ICEcoder.setTabWidths();
 
 		// If we need to set the editor sizes
@@ -119,14 +123,28 @@ var ICEcoder = {
 			// Resize the CodeMirror instances to match the window size
 			setTimeout(function(){
 				for (var i=0;i<top.ICEcoder.openFiles.length;i++) {
-				top.ICEcoder.content.contentWindow['cM'+ICEcoder.cMInstances[i]].setSize("100%",top.ICEcoder.content.style.height);
+					// Done the long way here as we need to call them in specific order to stop showing background and so avoiding a flicker effect
+					if (top.ICEcoder.splitPane) {
+						top.ICEcoder.content.contentWindow['cM'+ICEcoder.cMInstances[i]+'diff'].setSize("50%",top.ICEcoder.content.style.height);
+						top.ICEcoder.content.contentWindow['cM'+ICEcoder.cMInstances[i]].setSize("50%",top.ICEcoder.content.style.height);
+					} else {
+						top.ICEcoder.content.contentWindow['cM'+ICEcoder.cMInstances[i]].setSize("100%",top.ICEcoder.content.style.height);
+						top.ICEcoder.content.contentWindow['cM'+ICEcoder.cMInstances[i]+'diff'].setSize("0",top.ICEcoder.content.style.height);
+					}
 			}},4);
 		}
 	},
 
+	// Set the layout as split pane or not
+	setSplitPane: function(onOff) {
+		top.ICEcoder.splitPane = onOff == "on" ? true : false;
+		top.get('splitPaneControlsOff').style.opacity = top.ICEcoder.splitPane ? 0.5 : 1;
+		top.get('splitPaneControlsOn').style.opacity = top.ICEcoder.splitPane ? 1 : 0.5;
+		top.ICEcoder.setLayout();
+	},
+
 	// Set the width of the file manager on demand
 	changeFilesW: function(expandContract) {
-
 		if (!ICEcoder.lockedNav||ICEcoder.filesW==ICEcoder.minFilesW) {
 			if ("undefined" != typeof ICEcoder.changeFilesInt) {clearInterval(ICEcoder.changeFilesInt)};
 			ICEcoder.changeFilesInt = setInterval(function() {ICEcoder.changeFilesWStep(expandContract)},10);
@@ -187,81 +205,264 @@ var ICEcoder = {
 // EDITOR
 // ==============
 
+	// On key up
+	cMonFocus: function(thisCM,cMinstance) {
+		top.ICEcoder.getCaretPosition();
+		top.ICEcoder.updateCharDisplay();
+		top.ICEcoder.updateByteDisplay();
+		top.ICEcoder.editorFocusInstance = cMinstance;
+		top.ICEcoder.getCaretPosition();
+	},
+
+	// On blur
+	cMonBlur: function(thisCM,cMinstance) {
+		// Nothing as yet
+	},
+
+	// On key up
+	cMonKeyUp: function(thisCM,cMinstance) {
+		if ("undefined" != typeof top.doFind) {
+			clearInterval(top.doFind);
+		}
+		top.doFind = setTimeout(function() {
+			top.ICEcoder.findReplace(top.document.getElementById('find').value,true,false);
+		},500);
+		top.ICEcoder.getCaretPosition();
+		top.ICEcoder.updateCharDisplay();
+		top.ICEcoder.updateByteDisplay();
+	},
+
+	// On cursor activity
+	cMonCursorActivity: function(thisCM,cMinstance) {
+		var thisCMPrevLine;
+
+		top.ICEcoder.getCaretPosition();
+		top.ICEcoder.updateCharDisplay();
+		top.ICEcoder.updateByteDisplay();
+		thisCM.removeLineClass(top.ICEcoder['cMActiveLine'+cMinstance], "background");
+		if(thisCM.getCursor('start').line == thisCM.getCursor().line) {
+			top.ICEcoder['cMActiveLine'+cMinstance] = thisCM.addLineClass(thisCM.getCursor().line, "background","cm-s-activeLine");
+		}
+		if (top.ICEcoder.caretLocType=="CSS") {
+			top.ICEcoder.cssColorPreview();
+		}
+
+		thisCMPrevLine = top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? top.ICEcoder.prevLineDiff : top.ICEcoder.prevLine;
+		if (thisCMPrevLine != thisCM.getCursor().line && 
+			thisCM.getLine(thisCMPrevLine) && 
+			thisCM.getLine(thisCMPrevLine).length > 0 && 
+			thisCM.getLine(thisCMPrevLine).replace(/\s/g, '').length == 0) {
+				thisCM.replaceRange("",{line: thisCMPrevLine, ch: 0},{line: thisCMPrevLine, ch: 1000000});
+		}
+	},
+
+	// On change
+	cMonChange: function(thisCM,cMinstance,changeObj) {
+		var filepath, filename, fileExt;
+
+		// If we're not loading the file, it's a change, so update tab
+		if (!top.ICEcoder.loadingFile) {
+			top.ICEcoder.redoTabHighlight(top.ICEcoder.selectedTab);
+		}
+		top.ICEcoder.getCaretPosition();
+		top.ICEcoder.dontUpdateNest = false;
+		top.ICEcoder.updateCharDisplay();
+		top.ICEcoder.updateByteDisplay();
+		top.ICEcoder.updateNestingIndicator();
+		if (top.ICEcoder.findMode) {
+			top.ICEcoder.results.splice(top.ICEcoder.findResult,1);
+			top.document.getElementById('results').innerHTML = top.ICEcoder.results.length + " " + top.t['results'];
+			top.ICEcoder.findMode = false;
+		}
+		filepath = top.ICEcoder.openFiles[top.ICEcoder.selectedTab-1];
+		if (filepath) {
+			filename = filepath.substr(filepath.lastIndexOf("/")+1);
+			fileExt = filename.substr(filename.lastIndexOf(".")+1);
+			for (var i=changeObj.from.line; i<changeObj.from.line+changeObj.text.length; i++) {
+				top.ICEcoder.content.contentWindow.CodeMirror.doFold(thisCM.getLine(i).indexOf("{")>-1 ? "brace" : "xml" ,null ,"+" ,"-", true, thisCM, i);
+			}
+			if (changeObj.text[0] == "}" || changeObj.removed && changeObj.removed[0] == "}") {
+				cursor = thisCM.getSearchCursor("{",thisCM.getCursor(),false);
+				cursor.findPrevious();
+				for (var i=cursor.from().line; i<thisCM.getCursor().line; i++) {
+					top.ICEcoder.content.contentWindow.CodeMirror.doFold(thisCM.getLine(i).indexOf("{")>-1 ? "brace" : "xml" ,null ,"+" ,"-", true, thisCM, i);
+				}
+			}
+		}
+		if (top.ICEcoder.splitPane) {
+			top.ICEcoder.updateDiffs();
+		}
+		// Update HTML edited files live
+		if (filepath && top.ICEcoder.previewWindow.location) {
+			top.ICEcoder.updatePreviewWindow(thisCM,filepath,filename,fileExt);
+		}
+		// Update the title tag to indicate any changes
+		top.ICEcoder.indicateChanges();
+	},
+
+	// On input read
+	cMonInputRead: function(thisCM,cMinstance) {
+		if (top.ICEcoder.autoComplete == "keypress" && top.ICEcoder.codeAssist) {
+			clearTimeout(top.ICEcoder.debounce);
+			if (!thisCM.state.completionActive) {
+				top.ICEcoder.debounce = setTimeout(function() {
+					CodeMirror.commands.autocomplete(thisCM);
+				},200);
+			}
+		}
+	},
+
+	updateDiffs: function() {
+		var cM, cMdiff, mainText, diffText, sm, opcodes, cMmarks, markColor;
+
+		cM = top.ICEcoder.getcMInstance();
+		cMdiff = top.ICEcoder.getcMdiffInstance();
+
+		// Get the baseText and newText values from the two textboxes, and split them into lines
+		mainText = difflib.stringAsLines(cM.getValue());
+		diffText = difflib.stringAsLines(cMdiff.getValue());
+
+		// Create a SequenceMatcher instance that diffs the two sets of lines
+		sm = new difflib.SequenceMatcher(mainText, diffText);
+
+		// Get the opcodes from the SequenceMatcher instance
+		// Opcodes is a list of 3-tuples describing what changes should be made to the base text in order to yield the new text
+		opcodes = sm.get_opcodes();
+
+		cMmarks = cM.getAllMarks();
+		for (var i=0; i<cMmarks.length; i++) {
+			cMmarks[i].clear();
+		}
+		cMdiffmarks = cMdiff.getAllMarks();
+		for (var i=0; i<cMdiffmarks.length; i++) {
+			cMdiffmarks[i].clear();
+		}
+
+		for (var i=0; i<opcodes.length; i++) {
+			// We have a 'replace' or 'delete' status
+			if (opcodes[i][0] !== "equal") {
+				markColor = opcodes[i][0] == "replace" ? "diffGrey" : "diffGreen";
+				cM.markText({line: opcodes[i][1], ch: 0}, {line: opcodes[i][2]-1, ch: 1000000}, {className: markColor, startStyle: markColor, endStyle: markColor});
+				markColor = opcodes[i][0] == "replace" ? "diffGrey" : "diffRed";
+				cMdiff.markText({line: opcodes[i][3], ch: 0}, {line: opcodes[i][4]-1, ch: 1000000}, {className: markColor, startStyle: markColor, endStyle: markColor});
+			}
+		}
+	},
+
+	// Update preview window content
+	updatePreviewWindow: function(thisCM,filepath,filename,fileExt) {
+		if (top.ICEcoder.previewWindow.location.pathname==filepath) {
+			if (["htm","html","txt"].indexOf(fileExt) > -1) {
+				top.ICEcoder.previewWindow.document.documentElement.innerHTML = thisCM.getValue();
+			} else if (["md"].indexOf(fileExt) > -1) {
+				top.ICEcoder.previewWindow.document.documentElement.innerHTML = mmd(thisCM.getValue());
+			}
+		} else if (["css"].indexOf(fileExt) > -1) {
+			if (top.ICEcoder.previewWindow.document.documentElement.innerHTML.indexOf(filename) > -1) {
+				var css = thisCM.getValue();
+				var style = document.createElement('style');
+				style.type = 'text/css';
+				style.id = "ICEcoder"+filepath.replace(/\//g,"_");
+				if (style.styleSheet){
+					style.styleSheet.cssText = css;
+				} else {
+					style.appendChild(document.createTextNode(css));
+				}
+				if (top.ICEcoder.previewWindow.document.getElementById(style.id)) {
+					top.ICEcoder.previewWindow.document.documentElement.removeChild(top.ICEcoder.previewWindow.document.getElementById(style.id));
+				}
+				top.ICEcoder.previewWindow.document.documentElement.appendChild(style);
+			}
+		}
+		// Do the pesticide plugin if it exists
+		try {top.ICEcoder.doPesticide();} catch(err) {};
+	},
+
 	// Clean up our loaded code
 	contentCleanUp: function() {
-		var cM, content;
+		var cM, cMdiff, thisCM, content;
 
 		// Replace any temp /textarea value
 		cM = ICEcoder.getcMInstance();
-		content = cM.getValue();
+		cMdiff = ICEcoder.getcMdiffInstance();
+		thisCM = top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? cMdiff : cM;
+		content = thisCM.getValue();
 		content = content.replace(/<ICEcoder:\/:textarea>/g,'<\/textarea>');
 
 		// Then set the content in the editor & clear the history
-		cM.setValue(content);
-		cM.clearHistory();
-		top.ICEcoder.savedPoints[top.ICEcoder.selectedTab-1] = cM.changeGeneration();
+		thisCM.setValue(content);
+		thisCM.clearHistory();
+		top.ICEcoder.savedPoints[top.ICEcoder.selectedTab-1] = thisCM.changeGeneration();
 	},
 
 	// Undo last change
 	undo: function() {
-		var cM;
+		var cM, cMdiff, thisCM;
 
 		cM = ICEcoder.getcMInstance();
-		cM.undo();
+		cMdiff = ICEcoder.getcMdiffInstance();
+		thisCM = top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? cMdiff : cM;
+		thisCM.undo();
 	},
 
 	// Redo change
 	redo: function() {
-		var cM;
+		var cM, cMdiff, thisCM;
 
 		cM = ICEcoder.getcMInstance();
-		cM.redo();
+		cMdiff = ICEcoder.getcMdiffInstance();
+		thisCM = top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? cMdiff : cM;
+		thisCM.redo();
 	},
 
 	// Indent more/less
 	indent: function(moreLess) {
-		var cM;
+		var cM, cMdiff, thisCM;
 
 		cM = ICEcoder.getcMInstance();
+		cMdiff = ICEcoder.getcMdiffInstance();
+		thisCM = top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? cMdiff : cM;
 		if (moreLess=="more") {
-			top.ICEcoder.content.contentWindow.CodeMirror.commands.indentMore(cM);
+			top.ICEcoder.content.contentWindow.CodeMirror.commands.indentMore(thisCM);
 		} else {
-			top.ICEcoder.content.contentWindow.CodeMirror.commands.indentLess(cM);
+			top.ICEcoder.content.contentWindow.CodeMirror.commands.indentLess(thisCM);
 		}
 	},
 
 	// Move current line up/down
 	moveLines: function(dir) {
-		var cM, lineStart, lineEnd, swapLineNo, swapLine;
+		var cM, cMdiff, thisCM, lineStart, lineEnd, swapLineNo, swapLine;
 
 		cM = top.ICEcoder.getcMInstance();
+		cMdiff = top.ICEcoder.getcMdiffInstance();
+		thisCM = top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? cMdiff : cM;
 
 		// Get start & end lines plus the line we'll swap with
-		lineStart = cM.getCursor('start');
-		lineEnd = cM.getCursor('end');
+		lineStart = thisCM.getCursor('start');
+		lineEnd = thisCM.getCursor('end');
 		if (dir=="up" && lineStart.line>0) {swapLineNo = lineStart.line-1}
-		if (dir=="down" && lineEnd.line<cM.lineCount()-1) {swapLineNo = lineEnd.line+1}
+		if (dir=="down" && lineEnd.line<thisCM.lineCount()-1) {swapLineNo = lineEnd.line+1}
 
 		// If we have a line to swap with
 		if (!isNaN(swapLineNo)) {
 			// Get the content of the swap line and carry out the swap in a single operation
-			swapLine = cM.getLine(swapLineNo);
-			cM.operation(function() {
+			swapLine = thisCM.getLine(swapLineNo);
+			thisCM.operation(function() {
 				// Move lines in turn up
 				if (dir=="up") {
 					for (var i=lineStart.line; i<=lineEnd.line; i++) {
-						cM.replaceRange(cM.getLine(i),{line:i-1,ch:0},{line:i-1,ch:1000000});
+						thisCM.replaceRange(thisCM.getLine(i),{line:i-1,ch:0},{line:i-1,ch:1000000});
 					}
 				// ...or down
 				} else {
 					for (var i=lineEnd.line; i>=lineStart.line; i--) {
-						cM.replaceRange(cM.getLine(i),{line:i+1,ch:0},{line:i+1,ch:1000000});
+						thisCM.replaceRange(thisCM.getLine(i),{line:i+1,ch:0},{line:i+1,ch:1000000});
 					}
 				}
 				// Now swap our final line with the swap line to complete the move
-				cM.replaceRange(swapLine,{line: dir=="up" ? lineEnd.line : lineStart.line, ch: 0},{line: dir=="up" ? lineEnd.line : lineStart.line, ch:1000000});
+				thisCM.replaceRange(swapLine,{line: dir=="up" ? lineEnd.line : lineStart.line, ch: 0},{line: dir=="up" ? lineEnd.line : lineStart.line, ch:1000000});
 				// Finally set the moved selection
-				cM.setSelection(
+				thisCM.setSelection(
 					{line: lineStart.line+(dir=="up" ? -1 : 1), ch: lineStart.ch},
 					{line: lineEnd.line+(dir=="up" ? -1 : 1), ch: lineEnd.ch}
 				);
@@ -271,46 +472,56 @@ var ICEcoder = {
 
 	// Highlight specified line
 	highlightLine: function(line) {
-		var cM;
+		var cM, cMdiff, thisCM;
 
 		cM = top.ICEcoder.getcMInstance();
-		cM.setSelection({line:line,ch:0}, {line:line,ch:cM.lineInfo(line).text.length});
+		cMdiff = top.ICEcoder.getcMdiffInstance();
+		thisCM = top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? cMdiff : cM;
+		thisCM.setSelection({line:line,ch:0}, {line:line,ch:thisCM.lineInfo(line).text.length});
 	},
 
 	// Focus the editor
-	focus: function() {
-		var cM;
+	focus: function(diff) {
+		var cM, cMdiff, thisCM;
 
 		if (!(/iPhone|iPad|iPod/i.test(navigator.userAgent))) {
 			cM = top.ICEcoder.getcMInstance();
-			if (cM) {
-				cM.focus();
+			cMdiff = top.ICEcoder.getcMdiffInstance();
+			thisCM = diff ? cMdiff : cM;
+			if (thisCM) {
+				thisCM.focus();
 			}
 		}
 	},
 
 	// Go to a specific line number
 	goToLine: function(lineNo) {
-		var cM;
+		var cM, cMdiff, thisCM;
 
 		cM = ICEcoder.getcMInstance();
-		cM.setCursor(lineNo ? lineNo-1 : top.get('goToLineNo').value-1);
+		cMdiff = ICEcoder.getcMdiffInstance();
+		thisCM = top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? cMdiff : cM;
+
+		thisCM.setCursor(lineNo ? lineNo-1 : top.get('goToLineNo').value-1);
 		top.ICEcoder.focus();
 		return false;
 	},
 
 	// Comment/uncomment line or selected range on keypress
 	lineCommentToggle: function() {
-		var cM, cursorPos, linePos, lineContent, lCLen, adjustCursor;
+		var cM, cMdiff, thisCM, cursorPos, linePos, lineContent, lCLen, adjustCursor;
 
 		cM = ICEcoder.getcMInstance();
-		cursorPos = cM.getCursor().ch;
-		linePos = cM.getCursor().line;
-		lineContent = cM.getLine(linePos);
+		cMdiff = ICEcoder.getcMdiffInstance();
+		thisCM = top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? cMdiff : cM;
+
+		cursorPos = thisCM.getCursor().ch;
+		linePos = thisCM.getCursor().line;
+		lineContent = thisCM.getLine(linePos);
 		lCLen = lineContent.length;
 		adjustCursor = 2;
 
-		ICEcoder.lineCommentToggleSub(cM, cursorPos, linePos, lineContent, lCLen, adjustCursor);
+		ICEcoder.lineCommentToggleSub(thisCM, cursorPos, linePos, lineContent, lCLen, adjustCursor);
 	},
 
 	// Highlight or hide block upon roll over/out of nest positions
@@ -388,116 +599,130 @@ var ICEcoder = {
 
 	// Wrap our selected text/cursor with tags
 	tagWrapper: function(tag) {
-		var cM, tagStart, tagEnd, startLine, endLine;
+		var cM, cMdiff, thisCM, tagStart, tagEnd, startLine, endLine;
 
 		cM = ICEcoder.getcMInstance();
+		cMdiff = ICEcoder.getcMdiffInstance();
+		thisCM = top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? cMdiff : cM;
 		tagStart = tag;
 		tagEnd = tag;
 		if (tag=='div') {
-			startLine = cM.getCursor('start').line;
-			endLine = cM.getCursor().line;
-			cM.operation(function() {
-				cM.replaceSelection("<div>\n"+cM.getSelection()+"\n</div>","around");
+			startLine = thisCM.getCursor('start').line;
+			endLine = thisCM.getCursor().line;
+			thisCM.operation(function() {
+				thisCM.replaceSelection("<div>\n"+thisCM.getSelection()+"\n</div>","around");
 				for (var i=startLine+1; i<=endLine+1; i++) {
-					cM.indentLine(i);
+					thisCM.indentLine(i);
 				}
-				cM.indentLine(endLine+2,'prev');
-				cM.indentLine(endLine+2,'subtract');
+				thisCM.indentLine(endLine+2,'prev');
+				thisCM.indentLine(endLine+2,'subtract');
 			});
 		} else {
 			if (	['p','a','b','i','strong','em','h1','h2','h3','li'].indexOf(tag)>-1 && 
-				cM.getSelection().substr(0,tag.length+1) == "<"+tagStart && 
-				cM.getSelection().substr(-(tag.length+3)) == "</"+tagEnd+">") {
+				thisCM.getSelection().substr(0,tag.length+1) == "<"+tagStart && 
+				thisCM.getSelection().substr(-(tag.length+3)) == "</"+tagEnd+">") {
 					// Undo wrapper
-					cM.replaceSelection(cM.getSelection().substr(cM.getSelection().indexOf(">")+1,cM.getSelection().length-cM.getSelection().indexOf(">")-1-tag.length-3),"around");
+					thisCM.replaceSelection(thisCM.getSelection().substr(thisCM.getSelection().indexOf(">")+1,thisCM.getSelection().length-thisCM.getSelection().indexOf(">")-1-tag.length-3),"around");
 			} else {
 					if (tag=='a') {tagStart='a href=""';}
 					// Do wrapper
-					cM.replaceSelection("<"+tagStart+">"+cM.getSelection()+"</"+tagEnd+">","around");
-					if (tag=='a') {cM.setCursor({line:cM.getCursor('start').line,ch:cM.getCursor('start').ch+9})}
+					thisCM.replaceSelection("<"+tagStart+">"+thisCM.getSelection()+"</"+tagEnd+">","around");
+					if (tag=='a') {thisCM.setCursor({line:thisCM.getCursor('start').line,ch:thisCM.getCursor('start').ch+9})}
 			}
 		}
 	},
 
 	// Add a line break at end of current or specified line
 	addLineBreakAtEnd: function(line) {
-		var cM;
+		var cM,cMdiff, thisCM;
 
 		cM = ICEcoder.getcMInstance();
-		if (!line) {line = cM.getCursor().line};
-		cM.replaceRange(cM.getLine(line)+"<br>",{line:line,ch:0},{line:line,ch:1000000});
+		cMdiff = ICEcoder.getcMdiffInstance();
+		thisCM = top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? cMdiff : cM;
+		if (!line) {line = thisCM.getCursor().line};
+		thisCM.replaceRange(thisCM.getLine(line)+"<br>",{line:line,ch:0},{line:line,ch:1000000});
 	},
 
 	// Insert a line before and auto-indent
 	insertLineBefore: function(line) {
-		var cM;
+		var cM, cMdiff, thisCM;
 
 		cM = ICEcoder.getcMInstance();
-		if (!line) {line = cM.getCursor().line};
-		cM.operation(function() {
-			cM.replaceRange("\n"+cM.getLine(line),{line:line,ch:0},{line:line,ch:1000000});
-			cM.setCursor({line: cM.getCursor().line-1, ch: 0});
-			cM.execCommand('indentAuto');
+		cMdiff = ICEcoder.getcMdiffInstance();
+		thisCM = top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? cMdiff : cM;
+		if (!line) {line = thisCM.getCursor().line};
+		thisCM.operation(function() {
+			thisCM.replaceRange("\n"+thisCM.getLine(line),{line:line,ch:0},{line:line,ch:1000000});
+			thisCM.setCursor({line: thisCM.getCursor().line-1, ch: 0});
+			thisCM.execCommand('indentAuto');
 		});
 	},
 
 	// Insert a line after and auto-indent
 	insertLineAfter: function(line) {
-		var cM;
+		var cM, cMdiff, thisCM;
 
 		cM = ICEcoder.getcMInstance();
-		if (!line) {line = cM.getCursor().line};
-		cM.operation(function() {
-			cM.replaceRange(cM.getLine(line)+"\n",{line:line,ch:0},{line:line,ch:1000000});
-			cM.execCommand('indentAuto');
+		cMdiff = ICEcoder.getcMdiffInstance();
+		thisCM = top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? cMdiff : cM;
+		if (!line) {line = thisCM.getCursor().line};
+		thisCM.operation(function() {
+			thisCM.replaceRange(thisCM.getLine(line)+"\n",{line:line,ch:0},{line:line,ch:1000000});
+			thisCM.execCommand('indentAuto');
 		});
 	},
 
 	// Duplicate line
 	duplicateLines: function(line) {
-		var cM, ch, lineExtra, userSelStart, userSelEnd, lineBreak;
+		var cM, cMdiff, thisCM, ch, lineExtra, userSelStart, userSelEnd, lineBreak;
 
 		cM = ICEcoder.getcMInstance();
-		if (!line && cM.somethingSelected()) {
-			userSelStart = cM.getCursor('start');
-			userSelEnd = cM.getCursor('end');
-			lineExtra = userSelStart.line != userSelEnd.line && userSelEnd.ch == cM.getLine(userSelEnd.line).length ? "\n" : "";
-			cM.replaceSelection(cM.getSelection()+lineExtra+cM.getSelection(), "end");
-			cM.setSelection(userSelStart, userSelEnd);
+		cMdiff = ICEcoder.getcMdiffInstance();
+		thisCM = top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? cMdiff : cM;
+		if (!line && thisCM.somethingSelected()) {
+			userSelStart = thisCM.getCursor('start');
+			userSelEnd = thisCM.getCursor('end');
+			lineExtra = userSelStart.line != userSelEnd.line && userSelEnd.ch == thisCM.getLine(userSelEnd.line).length ? "\n" : "";
+			thisCM.replaceSelection(thisCM.getSelection()+lineExtra+thisCM.getSelection(), "end");
+			thisCM.setSelection(userSelStart, userSelEnd);
 		} else {
-			if (!line) {line = cM.getCursor().line};
-			ch = cM.getCursor().ch;
-			cM.replaceRange(cM.getLine(line)+"\n"+cM.getLine(line),{line:line,ch:0},{line:line,ch:1000000});
-			cM.setCursor(line+1,ch);
+			if (!line) {line = thisCM.getCursor().line};
+			ch = thisCM.getCursor().ch;
+			thisCM.replaceRange(thisCM.getLine(line)+"\n"+thisCM.getLine(line),{line:line,ch:0},{line:line,ch:1000000});
+			thisCM.setCursor(line+1,ch);
 		}
 	},
 
 	// Remove line
 	removeLines: function(line) {
-		var cM, ch;
+		var cM, cMdiff, thisCM, ch;
 
 		cM = ICEcoder.getcMInstance();
-		if (!line && cM.somethingSelected()) {
-			cM.replaceSelection("","end");
+		cMdiff = ICEcoder.getcMdiffInstance();
+		thisCM = top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? cMdiff : cM;
+		if (!line && thisCM.somethingSelected()) {
+			thisCM.replaceSelection("","end");
 		} else {
-			if (!line) {line = cM.getCursor().line};
-			ch = cM.getCursor().ch;
-			cM.execCommand('deleteLine');
-			cM.setCursor(line-1,ch);
+			if (!line) {line = thisCM.getCursor().line};
+			ch = thisCM.getCursor().ch;
+			thisCM.execCommand('deleteLine');
+			thisCM.setCursor(line-1,ch);
 		}
 	},
 
 	// Jump to and highlight the function definition current token
 	jumpToDefinition: function() {
-		var cM, tokenString, defVars;
+		var cM, cMdiff, thisCM, tokenString, defVars;
 
 		cM = ICEcoder.getcMInstance();
-		tokenString = cM.getTokenAt(cM.getCursor()).string;
+		cMdiff = ICEcoder.getcMdiffInstance();
+		thisCM = top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? cMdiff : cM;
+		tokenString = thisCM.getTokenAt(thisCM.getCursor()).string;
 
-		if (cM.somethingSelected() && top.ICEcoder.origCurorPos) {
-			cM.setCursor(top.ICEcoder.origCurorPos);
+		if (thisCM.somethingSelected() && top.ICEcoder.origCurorPos) {
+			thisCM.setCursor(top.ICEcoder.origCurorPos);
 		} else {
-			top.ICEcoder.origCurorPos = cM.getCursor();
+			top.ICEcoder.origCurorPos = thisCM.getCursor();
 			defVars = [
 				"var "+tokenString,
 				"function "+tokenString,
@@ -518,32 +743,41 @@ var ICEcoder = {
 
 	// Autocomplete
 	autocomplete: function() {
-		var cM;
+		var cM, cMdiff, thisCM;
 
 		cM = ICEcoder.getcMInstance();
-		top.ICEcoder.content.contentWindow.CodeMirror.commands.autocomplete(cM);
+		cMdiff = ICEcoder.getcMdiffInstance();
+		thisCM = top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? cMdiff : cM;
+		top.ICEcoder.content.contentWindow.CodeMirror.commands.autocomplete(thisCM);
 	},
 
 	// Paste a URL, locally or absolutely if CTRL/Cmd key down
 	pasteURL: function(url) {
-		var cM;
+		var cM, cMdiff, thisCM;
 
-		cM = ICEcoder.getcMInstance();
+		cM = top.ICEcoder.getcMInstance();
+		cMdiff = top.ICEcoder.getcMdiffInstance();
+		thisCM = top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? cMdiff : cM;
 		if(top.ICEcoder.draggingWithKey == "CTRL") {
 			url = window.location.protocol + "//" + window.location.hostname + url;
 		}
-		cM.replaceSelection(url,"around");
+		thisCM.replaceSelection(url,"around");
 	},
 
 	// Search for selected text online
 	searchForSelected: function() {
+		var cM, cMdiff, thisCM;
+
+		cM = top.ICEcoder.getcMInstance();
+		cMdiff = top.ICEcoder.getcMdiffInstance();
+		thisCM = top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? cMdiff : cM;
 		if (top.ICEcoder.caretLocType) {
-			if (top.ICEcoder.getcMInstance().getSelection() != "") {
+			if (thisCM.getSelection() != "") {
 				var searchPrefix = top.ICEcoder.caretLocType.toLowerCase()+" ";
 				if (top.ICEcoder.caretLocType=="Content") {
 					searchPrefix = "";
 				}
-				window.open("http://www.google.com/#output=search&q="+searchPrefix+top.ICEcoder.getcMInstance().getSelection());
+				window.open("http://www.google.com/#output=search&q="+searchPrefix+thisCM.getSelection());
 			} else {
 				top.ICEcoder.message(top.t['No text selected...']);
 			}
@@ -1176,7 +1410,7 @@ var ICEcoder = {
 
 	// Find & replace text according to user selections
 	findReplace: function(findString,resultsOnly,buttonClick) {
-		var find, replace, results, cM, content, scrollBarVisible, cursor, avgBlockH, addPadding, rBlocks, blockColor, replaceQS, targetQS, filesQS;
+		var find, replace, results, cM, cMdiff, thisCM, content, scrollBarVisible, cursor, avgBlockH, addPadding, rBlocks, blockColor, replaceQS, targetQS, filesQS;
 
 		// Determine our find & replace strings and results display
 		find		= findString.toLowerCase();
@@ -1185,20 +1419,22 @@ var ICEcoder = {
 
 		// If we have something to find in currrent document
 		cM = ICEcoder.getcMInstance();
-		if (cM && find.length>0 && document.findAndReplace.target.value==top.t['this document']) {
-			content = cM.getValue().toLowerCase();
+		cMdiff = ICEcoder.getcMdiffInstance();
+		thisCM = top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? cMdiff : cM;
+		if (thisCM && find.length>0 && document.findAndReplace.target.value==top.t['this document']) {
+			content = thisCM.getValue().toLowerCase();
 			// Find & replace the next instance, or all?
 			if (document.findAndReplace.connector.value==top.t['and'] && buttonClick) {
-				if (document.findAndReplace.replaceAction.value==top.t['replace'] && cM.getSelection().toLowerCase()==find) {
-					cM.replaceSelection(replace,"around");
+				if (document.findAndReplace.replaceAction.value==top.t['replace'] && thisCM.getSelection().toLowerCase()==find) {
+					thisCM.replaceSelection(replace,"around");
 				} else if (document.findAndReplace.replaceAction.value==top.t['replace all']) {
 					var rExp = new RegExp(find,"gi");
-					cM.setValue(cM.getValue().replace(rExp,replace));
+					thisCM.setValue(thisCM.getValue().replace(rExp,replace));
 				}
 			}
 
 			// Get the content again, as it might of changed
-			content = cM.getValue().toLowerCase();
+			content = thisCM.getValue().toLowerCase();
 			if (!top.ICEcoder.findMode||find!=top.ICEcoder.lastsearch) {
 				ICEcoder.results = [];
 				ICEcoder.resultsLines = [];
@@ -1206,8 +1442,8 @@ var ICEcoder = {
 				for (var i=0;i<content.length;i++) {
 					if (content.substr(i,find.length)==find && ICEcoder.results.indexOf(i) == -1) {
 						ICEcoder.results.push(i);
-						if (ICEcoder.resultsLines.indexOf(cM.posFromIndex(i).line+1)==-1) {
-							ICEcoder.resultsLines.push(cM.posFromIndex(i).line+1);
+						if (ICEcoder.resultsLines.indexOf(thisCM.posFromIndex(i).line+1)==-1) {
+							ICEcoder.resultsLines.push(thisCM.posFromIndex(i).line+1);
 						}
 					}
 				}
@@ -1219,7 +1455,7 @@ var ICEcoder = {
 			// If we have results
 			if (ICEcoder.results.length>0) {
 				// Detect if we have a scrollbar
-				scrollBarVisible = cM.getScrollInfo().height > cM.getScrollInfo().clientHeight;
+				scrollBarVisible = thisCM.getScrollInfo().height > thisCM.getScrollInfo().clientHeight;
 
 				// Show results only
 				if (resultsOnly) {
@@ -1229,7 +1465,7 @@ var ICEcoder = {
 					// Find our cursor position relative to results
 					ICEcoder.findResult = 0;
 					for (var i=0;i<ICEcoder.results.length;i++) {
-						if (ICEcoder.results[i]<cM.indexFromPos(cM.getCursor())) {
+						if (ICEcoder.results[i]<thisCM.indexFromPos(thisCM.getCursor())) {
 							ICEcoder.findResult++;
 						}
 					}
@@ -1238,28 +1474,28 @@ var ICEcoder = {
 					// Update results display
 					results.innerHTML = "Highlighted result "+(ICEcoder.findResult+1)+" of "+ICEcoder.results.length+" results";
 
-					cursor = cM.getSearchCursor(find,cM.getCursor(),true);
+					cursor = thisCM.getSearchCursor(find,thisCM.getCursor(),true);
 					cursor.findNext();
 					if (!cursor.from()) {
-						cursor = cM.getSearchCursor(find,{line:0,ch:0},true);
+						cursor = thisCM.getSearchCursor(find,{line:0,ch:0},true);
 						cursor.findNext();
 					}
 					// Finally, highlight our selection
-					cM.setSelection(cursor.from(), cursor.to());
+					thisCM.setSelection(cursor.from(), cursor.to());
 					top.ICEcoder.focus();
 					top.ICEcoder.findMode = true;
 				}
 
 				// Display the find results bar
 				// The avg block is either line height or fraction of space available
-				avgBlockH = !scrollBarVisible ? cM.defaultTextHeight() : parseInt(top.ICEcoder.content.style.height,10)/cM.lineCount();
+				avgBlockH = !scrollBarVisible ? thisCM.defaultTextHeight() : parseInt(top.ICEcoder.content.style.height,10)/thisCM.lineCount();
 				// Need to add padding if there's no scrollbar, so current line highlighting lines up with it
-				addPadding = !scrollBarVisible ? cM.heightAtLine(0) : 0;
+				addPadding = !scrollBarVisible ? thisCM.heightAtLine(0) : 0;
 				// Place to edge of screen or scrollbar
 				top.ICEcoder.content.contentWindow.document.getElementById('resultsBar').style.right = !scrollBarVisible ? "0" : "17px";
 				rBlocks = "";
-				for (var i=1; i<=cM.lineCount(); i++) {
-					blockColor = ICEcoder.resultsLines.indexOf(i)>-1 ? cM.getCursor().line+1 == i ? "#b00" : "#888" : "transparent"
+				for (var i=1; i<=thisCM.lineCount(); i++) {
+					blockColor = ICEcoder.resultsLines.indexOf(i)>-1 ? thisCM.getCursor().line+1 == i ? "#b00" : "#888" : "transparent"
 					rBlocks += '<div style="position: absolute; display: block; width: 5px; height:'+avgBlockH+'px; background: '+blockColor+'; top: '+parseInt((avgBlockH*(i-1))+addPadding,10)+'px"></div>';
 				}
 				top.ICEcoder.content.contentWindow.document.getElementById('resultsBar').innerHTML = rBlocks;
@@ -1312,14 +1548,17 @@ var ICEcoder = {
 
 	// Work out the nesting depth location on demand and update our display if required
 	getNestLocation: function(updateNestDisplay) {
-		var cM, nestCheck, state, cx, startPos, fileName;
+		var cM, cMdiff, thisCM, nestCheck, state, cx, startPos, fileName;
 
 		cM = ICEcoder.getcMInstance();
-		if (cM) {
-			nestCheck = cM.getValue();
+		cMdiff = ICEcoder.getcMdiffInstance();
+		thisCM = top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? cMdiff : cM;
+
+		if (thisCM) {
+			nestCheck = thisCM.getValue();
 
 			// Get the token state at our cursor
-			state = cM.getTokenAt(cM.getCursor()).state;
+			state = thisCM.getTokenAt(thisCM.getCursor()).state;
 			cx = false;
 
 			// XML
@@ -1360,14 +1599,17 @@ var ICEcoder = {
 
 	// Get the caret position
 	getCaretPosition: function() {
-		var cM, line, ch, chPos;
+		var cM, cMdiff, thisCM, line, ch, chPos;
 
 		cM = ICEcoder.getcMInstance();
-		line = cM.getCursor().line;
-		ch = cM.getCursor().ch;
+		cMdiff = ICEcoder.getcMdiffInstance();
+		thisCM = top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? cMdiff : cM;
+
+		line = thisCM.getCursor().line;
+		ch = thisCM.getCursor().ch;
 		chPos = 0;
 		for (var i=0;i<line;i++) {
-			chPos += cM.getLine(i).length+1;
+			chPos += thisCM.getLine(i).length+1;
 		}
 		ICEcoder.caretPos=(chPos+ch-1);
 		ICEcoder.getNestLocation('yes');
@@ -1375,16 +1617,23 @@ var ICEcoder = {
 
 	// Update the code type, line & character display
 	updateCharDisplay: function() {
-		var cM;
+		var cM, cMdiff, thisCM;
 
 		cM = ICEcoder.getcMInstance();
+		cMdiff = ICEcoder.getcMdiffInstance();
+		thisCM = top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? cMdiff : cM;
 		ICEcoder.caretLocationType();
-		ICEcoder.charDisplay.innerHTML = ICEcoder.caretLocType + ", Line: " + (cM.getCursor().line+1) + ", Char: " + cM.getCursor().ch;
+		ICEcoder.charDisplay.innerHTML = ICEcoder.caretLocType + ", Line: " + (thisCM.getCursor().line+1) + ", Char: " + thisCM.getCursor().ch;
 	},
 
 	// Update the byte display
 	updateByteDisplay: function() {
-		ICEcoder.byteDisplay.innerHTML = ICEcoder.getcMInstance().getValue().length.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ",") + " bytes";
+		var cM, cMdiff, thisCM;
+
+		cM = ICEcoder.getcMInstance();
+		cMdiff = ICEcoder.getcMdiffInstance();
+		thisCM = top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? cMdiff : cM;
+		ICEcoder.byteDisplay.innerHTML = thisCM.getValue().length.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ",") + " bytes";
 	},
 
 	// Toggle the char/byte display
@@ -1412,6 +1661,21 @@ var ICEcoder = {
 		];
 	},
 
+	// Determine the CodeMirror instance we're using
+	getcMdiffInstance: function(tab) {
+		return top.ICEcoder.content.contentWindow[
+			(// target specific tab
+			!isNaN(tab)
+			? 'cM'+ICEcoder.cMInstances[tab-1]
+			// new tab or selected tab
+			: tab=="new"||(tab!="new" && ICEcoder.openFiles.length>0)
+			? 'cM'+ICEcoder.cMInstances[ICEcoder.selectedTab-1]
+			// fallback to first tab
+			: 'cM1')
+			+ 'diff'
+		];
+	},
+
 	// Get the mouse position
 	getMouseXY: function(e,area) {
 		var tempX, tempY;
@@ -1475,14 +1739,17 @@ var ICEcoder = {
 
 	// Show a CSS color block next to our text cursor
 	cssColorPreview: function() {
-		var cM, string, rx, match, oldBlock, newBlock;
+		var cM, cMdiff, thisCM, string, rx, match, oldBlock, newBlock;
 
 		cM = ICEcoder.getcMInstance();
-		if (cM) {
-			string = cM.getLine(cM.getCursor().line);
+		cMdiff = ICEcoder.getcMdiffInstance();
+		thisCM = top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? cMdiff : cM;
+
+		if (thisCM) {
+			string = thisCM.getLine(thisCM.getCursor().line);
 			rx = /(#[\da-f]{3}(?:[\da-f]{3})?\b|\b(?:rgb|hsl)a?\([\s\d%,.-]+\)|\b[a-z]+\b)/gi;
 
-			while((match = rx.exec(string)) && cM.getCursor().ch > match.index+match[0].length);
+			while((match = rx.exec(string)) && thisCM.getCursor().ch > match.index+match[0].length);
 
 			oldBlock = top.get('content').contentWindow.document.getElementById('cssColor');
 			if (oldBlock) {oldBlock.parentNode.removeChild(oldBlock)};
@@ -1498,7 +1765,7 @@ var ICEcoder = {
 				newBlock.onclick = function() {top.ICEcoder.showColorPicker(match[0])};
 				if (newBlock.style.backgroundColor=="") {newBlock.style.display = "none"};
 				top.get('header').appendChild(newBlock);
-				cM.addWidget(cM.getCursor(), top.get('cssColor'), true);
+				thisCM.addWidget(thisCM.getCursor(), top.get('cssColor'), true);
 			}
 		}
 	},
@@ -1574,11 +1841,13 @@ var ICEcoder = {
 
 	// Insert new color value
 	insertColorValue: function(color) {
-		var cM, cursor;
+		var cM, cMdiff, thisCM, cursor;
 
 		cM = ICEcoder.getcMInstance();
-		cursor = cM.getTokenAt(cM.getCursor());
-		cM.replaceRange(color,{line:cM.getCursor().line,ch:cursor.start},{line:cM.getCursor().line,ch:1000000});
+		cMdiff = ICEcoder.getcMdiffInstance();
+		thisCM = top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? cMdiff : cM;
+		cursor = thisCM.getTokenAt(thisCM.getCursor());
+		thisCM.replaceRange(color,{line:thisCM.getCursor().line,ch:cursor.start},{line:thisCM.getCursor().line,ch:1000000});
 	},
 
 	// Change opacity of the file manager icons
@@ -1844,10 +2113,18 @@ var ICEcoder = {
 		top.ICEcoder.indentWithTabs = indentWithTabs;
 		top.ICEcoder.indentSize = indentSize;
 		for (var i=0;i<ICEcoder.cMInstances.length;i++) {
+			// Main pane
 			ICEcoder.content.contentWindow['cM'+ICEcoder.cMInstances[i]].setOption("lineWrapping", top.ICEcoder.lineWrapping);
 			ICEcoder.content.contentWindow['cM'+ICEcoder.cMInstances[i]].setOption("indentWithTabs", top.ICEcoder.indentWithTabs);
 			ICEcoder.content.contentWindow['cM'+ICEcoder.cMInstances[i]].setOption("indentUnit", top.ICEcoder.indentSize);
 			ICEcoder.content.contentWindow['cM'+ICEcoder.cMInstances[i]].setOption("tabSize", top.ICEcoder.indentSize);
+			ICEcoder.content.contentWindow['cM'+ICEcoder.cMInstances[i]].refresh();
+			// Diff pane
+			ICEcoder.content.contentWindow['cM'+ICEcoder.cMInstances[i]+'diff'].setOption("lineWrapping", top.ICEcoder.lineWrapping);
+			ICEcoder.content.contentWindow['cM'+ICEcoder.cMInstances[i]+'diff'].setOption("indentWithTabs", top.ICEcoder.indentWithTabs);
+			ICEcoder.content.contentWindow['cM'+ICEcoder.cMInstances[i]+'diff'].setOption("indentUnit", top.ICEcoder.indentSize);
+			ICEcoder.content.contentWindow['cM'+ICEcoder.cMInstances[i]+'diff'].setOption("tabSize", top.ICEcoder.indentSize);
+			ICEcoder.content.contentWindow['cM'+ICEcoder.cMInstances[i]+'diff'].refresh();
 		}
 
 		if (tagWrapperCommand != top.ICEcoder.tagWrapperCommand) {
@@ -1924,16 +2201,18 @@ var ICEcoder = {
 	// Open/show the preview window
 	openPreviewWindow: function() {
 		if (top.ICEcoder.openFiles.length>0) {
-			var cM, filepath, filename, fileExt;
+			var cM, cMdiff, thisCM, filepath, filename, fileExt;
 
 			filepath = top.ICEcoder.openFiles[top.ICEcoder.selectedTab-1];
 			filename = filepath.substr(filepath.lastIndexOf("/")+1);
 			fileExt = filename.substr(filename.lastIndexOf(".")+1);
 			cM = ICEcoder.getcMInstance();
+			cMdiff = ICEcoder.getcMdiffInstance();
+			thisCM = top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? cMdiff : cM;
 
 			top.ICEcoder.previewWindow = window.open(filepath,"previewWindow");
 			if (["md"].indexOf(fileExt) > -1) {
-				top.ICEcoder.previewWindow.onload = function() {top.ICEcoder.previewWindow.document.documentElement.innerHTML = mmd(cM.getValue())};
+				top.ICEcoder.previewWindow.onload = function() {top.ICEcoder.previewWindow.document.documentElement.innerHTML = mmd(thisCM.getValue())};
 			} else {
 				top.ICEcoder.previewWindow.onload = function() {
 					// Do the pesticide plugin if it exists
@@ -2093,16 +2372,18 @@ var ICEcoder = {
 
 	// Print code of current tab
 	printCode: function() {
-		var cM, printIFrame;
+		var cM, cMdiff, thisCM, printIFrame;
 
 		cM = top.ICEcoder.getcMInstance();
+		cMdiff = top.ICEcoder.getcMdiffInstance();
+		thisCM = top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? cMdiff : cM;
 		printIFrame = top.ICEcoder.filesFrame.contentWindow.frames['fileControl'];
 		// Print page content injected into iFrame, escaped with pre and xssClean
-		printIFrame.window.document.body.innerHTML = '<!DOCTYPE html><head><title>ICEcoder code output</title></head><body><pre style="white-space: pre-wrap">'+top.ICEcoder.xssClean(cM.getValue())+'</pre></body></html>';
+		printIFrame.window.document.body.innerHTML = '<!DOCTYPE html><head><title>ICEcoder code output</title></head><body><pre style="white-space: pre-wrap">'+top.ICEcoder.xssClean(thisCM.getValue())+'</pre></body></html>';
 		printIFrame.focus();
 		printIFrame.print();
 		// Focus back on code
-		cM.focus();
+		thisCM.focus();
 	},
 
 	// Update the title tag to indicate any changes
@@ -2128,26 +2409,32 @@ var ICEcoder = {
 
 	// Change tabs by switching visibility of instances
 	switchTab: function(newTab,noFocus) {
-		var cM;
+		var cM, cMdiff, thisCM;
 
 		// Identify tab that's currently selected & get the instance
 		ICEcoder.selectedTab = newTab;
 		cM = ICEcoder.getcMInstance();
+		cMdiff = ICEcoder.getcMdiffInstance();
+		thisCM = top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? cMdiff : cM;
 
-		if (cM) {
+		if (thisCM) {
 			// Switch mode to HTML, PHP, CSS etc
 			ICEcoder.switchMode();
 
 			// Set all cM instances to be hidden, then make our selected instance visible
 			for (var i=0;i<ICEcoder.cMInstances.length;i++) {
 				ICEcoder.content.contentWindow['cM'+ICEcoder.cMInstances[i]].getWrapperElement().style.display = "none";
+				ICEcoder.content.contentWindow['cM'+ICEcoder.cMInstances[i]+'diff'].getWrapperElement().style.display = "none";
 			}
 			cM.setOption('theme',top.ICEcoder.theme);
+			cMdiff.setOption('theme',top.ICEcoder.theme + " diff");
 			cM.getWrapperElement().style.display = "block";
+			cMdiff.getWrapperElement().style.display = "block";
 
 			// Focus on & refresh our selected instance
 			if (!noFocus) {setTimeout(function() {top.ICEcoder.focus();},4);}
 			cM.refresh();
+			cMdiff.refresh();
 
 			// Highlight the selected tab
 			ICEcoder.redoTabHighlight(ICEcoder.selectedTab);
@@ -2180,8 +2467,8 @@ var ICEcoder = {
 		cM = ICEcoder.getcMInstance('new');
 		ICEcoder.switchTab(ICEcoder.openFiles.length);
 
-		cM.removeLineClass(ICEcoder['cMActiveLine'+ICEcoder.cMInstances[top.ICEcoder.selectedTab-1]], "background");
-		ICEcoder['cMActiveLine'+ICEcoder.selectedTab] = cM.addLineClass(0, "background", "cm-s-activeLine");
+		cM.removeLineClass(ICEcoder['cMActiveLinecM'+ICEcoder.cMInstances[top.ICEcoder.selectedTab-1]], "background");
+		ICEcoder['cMActiveLinecM'+ICEcoder.selectedTab] = cM.addLineClass(0, "background", "cm-s-activeLine");
 		ICEcoder.nextcMInstance++;
 	},
 
@@ -2267,12 +2554,13 @@ var ICEcoder = {
 
 	// Close the tab upon request
 	closeTab: function(closeTabNum, dontSetPV, dontAsk) {
-		var cM, okToRemove, closeFileName;
+		var cM, cMdiff, thisCM, okToRemove, closeFileName;
 
 		// If we haven't specified, close current tab
 		if (!closeTabNum) {closeTabNum = top.ICEcoder.selectedTab};
 
 		cM = ICEcoder.getcMInstance();
+		cMdiff = ICEcoder.getcMdiffInstance();
 		okToRemove = true;
 		if (!dontAsk && ICEcoder.savedPoints[closeTabNum-1]!=top.ICEcoder.getcMInstance(closeTabNum).changeGeneration()) {
 			okToRemove = top.ICEcoder.ask(top.t['You have made...']);
@@ -2291,6 +2579,7 @@ var ICEcoder = {
 			}
 			// hide the instance we're closing by setting the hide class and removing from the array
 			ICEcoder.content.contentWindow['cM'+top.ICEcoder.cMInstances[closeTabNum-1]].getWrapperElement().style.display = "none";
+			ICEcoder.content.contentWindow['cM'+top.ICEcoder.cMInstances[closeTabNum-1]+'diff'].getWrapperElement().style.display = "none";
 			top.ICEcoder.cMInstances.splice(closeTabNum-1,1);
 			// clear the rightmost tab (or only one left in a 1 tab scenario) & remove from the array
 			top.get('tab'+ICEcoder.openFiles.length).style.display = "none";
@@ -2671,7 +2960,7 @@ var ICEcoder = {
 			// Space outisde of editor (Focus on editor)
 			} else if(key==32 && area!="content" && ["find","replace"].indexOf(document.activeElement.id)==-1) {
 				if (top.ICEcoder.getcMInstance()) {
-					top.ICEcoder.focus();
+					top.ICEcoder.focus(top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? true : false);
 				}
 	        		return false;
 
@@ -2718,13 +3007,15 @@ var ICEcoder = {
 
 	// Add snippet code completion
 	addSnippet: function() {
-		var cM, lineNo, whiteSpace, content;
+		var cM, cMdiff, thisCM, lineNo, whiteSpace, content;
 
 		// Get line content after trimming whitespace
 		cM = ICEcoder.getcMInstance();
-		lineNo = cM.getCursor().line;
-		whiteSpace = cM.getLine(lineNo).length - cM.getLine(lineNo).replace(/^\s\s*/, '').length;
-		content = cM.getLine(lineNo).slice(whiteSpace);
+		cMdiff = ICEcoder.getcMdiffInstance();
+		thisCM = top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? cMdiff : cM;
+		lineNo = thisCM.getCursor().line;
+		whiteSpace = thisCM.getLine(lineNo).length - thisCM.getLine(lineNo).replace(/^\s\s*/, '').length;
+		content = thisCM.getLine(lineNo).slice(whiteSpace);
 		// function snippet
 		if (content.slice(0,8)=="function") {
 			top.ICEcoder.doSnippet('function','function VAR() {\nINDENT\tCURSOR\nINDENT}');
@@ -2739,26 +3030,28 @@ var ICEcoder = {
 
 	// Action a snippet
 	doSnippet: function(tgtString,replaceString) {
-		var cM, lineNo, lineContents, remainder, strPos, replacedLine, whiteSpace, curPos, sPos, lineNoCount;
+		var cM, cMdiff, thisCM, lineNo, lineContents, remainder, strPos, replacedLine, whiteSpace, curPos, sPos, lineNoCount;
 
 		// Get line contents
-		cM = top.ICEcoder.getcMInstance();
-		lineNo = cM.getCursor().line;
-		lineContents = cM.getLine(lineNo);
+		cM = ICEcoder.getcMInstance();
+		cMdiff = ICEcoder.getcMdiffInstance();
+		thisCM = top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? cMdiff : cM;
+		lineNo = thisCM.getCursor().line;
+		lineContents = thisCM.getLine(lineNo);
 
 		// Find our target string
 		if (lineContents.indexOf(tgtString)>-1) {
 			// Get text on the line from our target to the end
-			remainder = cM.getLine(lineNo);
+			remainder = thisCM.getLine(lineNo);
 			strPos = remainder.indexOf(tgtString);
 			remainder = remainder.slice(remainder.indexOf(tgtString)+tgtString.length+1);
 			// Replace the function name if any
 			replaceString = replaceString.replace(/VAR/g,remainder);
 			// Get replaced string from start to our strPos
-			replacedLine = cM.getLine(lineNo).slice(0,strPos);
+			replacedLine = thisCM.getLine(lineNo).slice(0,strPos);
 			// Trim whitespace from start
-			whiteSpace = cM.getLine(lineNo).length - cM.getLine(lineNo).replace(/^\s\s*/, '').length;
-			whiteSpace = cM.getLine(lineNo).slice(0,whiteSpace);
+			whiteSpace = thisCM.getLine(lineNo).length - thisCM.getLine(lineNo).replace(/^\s\s*/, '').length;
+			whiteSpace = thisCM.getLine(lineNo).slice(0,whiteSpace);
 			// Replace indent with whatever whitespace we have
 			replaceString = replaceString.replace(/INDENT/g,whiteSpace);
 			replacedLine += replaceString;
@@ -2773,10 +3066,10 @@ var ICEcoder = {
 				}
 			}
 			// Clear the cursor string and set the cursor there
-			cM.replaceRange(replacedLine.replace("CURSOR",""),{line:lineNo,ch:0},{line:lineNo,ch:1000000});
-			cM.setCursor(lineNoCount,curPos);
+			thisCM.replaceRange(replacedLine.replace("CURSOR",""),{line:lineNo,ch:0},{line:lineNo,ch:1000000});
+			thisCM.setCursor(lineNoCount,curPos);
 			// Finally, focus on the editor
-			top.ICEcoder.focus();
+			top.ICEcoder.focus(top.ICEcoder.editorFocusInstance.indexOf('diff') > -1 ? true : false);
 		}
 	}
 };
\ No newline at end of file