diff --git a/inspectrum.pro b/inspectrum.pro
index 9d012b4..01fb30a 100644
--- a/inspectrum.pro
+++ b/inspectrum.pro
@@ -4,5 +4,5 @@ TARGET = inspectrum
 TEMPLATE = app
 
 LIBS += -lfftw3f
-HEADERS += mainwindow.h inputsource.h spectrogram.h
-SOURCES += main.cpp mainwindow.cpp inputsource.cpp spectrogram.cpp
+HEADERS += mainwindow.h inputsource.h spectrogram.h spectrogramcontrols.h
+SOURCES += main.cpp mainwindow.cpp inputsource.cpp spectrogram.cpp spectrogramcontrols.cpp
diff --git a/mainwindow.cpp b/mainwindow.cpp
index 409eb39..67be37d 100644
--- a/mainwindow.cpp
+++ b/mainwindow.cpp
@@ -7,4 +7,10 @@ MainWindow::MainWindow()
     setWindowTitle(tr("inspectrum"));
     scrollArea.setWidget(&spectrogram);
     setCentralWidget(&scrollArea);
-}
+
+    dock = new SpectrogramControls(tr("Controls"), this);
+    dock->setAllowedAreas(Qt::LeftDockWidgetArea | Qt::RightDockWidgetArea);
+    addDockWidget(Qt::LeftDockWidgetArea, dock);
+
+    connect(dock, SIGNAL(fftSizeChanged(int)), &spectrogram, SLOT(setFFTSize(int)));
+}
\ No newline at end of file
diff --git a/mainwindow.h b/mainwindow.h
index bc7628f..9424354 100644
--- a/mainwindow.h
+++ b/mainwindow.h
@@ -3,6 +3,7 @@
 #include <QMainWindow>
 #include <QScrollArea>
 #include "spectrogram.h"
+#include "spectrogramcontrols.h"
 
 class MainWindow : public QMainWindow
 {
@@ -14,4 +15,5 @@ public:
 private:
     QScrollArea scrollArea;
     Spectrogram spectrogram;
+    SpectrogramControls *dock;
 };
\ No newline at end of file
diff --git a/spectrogram.cpp b/spectrogram.cpp
index 2a03a7a..31af904 100644
--- a/spectrogram.cpp
+++ b/spectrogram.cpp
@@ -49,4 +49,11 @@ void Spectrogram::paintEvent(QPaintEvent *event)
 	}
 
 	qDebug() << "Paint: " << timer.elapsed() << "ms";
+}
+
+void Spectrogram::setFFTSize(int size)
+{
+	inputSource->setFFTSize(size);
+	update();
+	resize(inputSource->GetWidth(), inputSource->GetHeight());
 }
\ No newline at end of file
diff --git a/spectrogram.h b/spectrogram.h
index 165d11b..54a588f 100644
--- a/spectrogram.h
+++ b/spectrogram.h
@@ -4,13 +4,19 @@
 #include "inputsource.h"
 
 class Spectrogram : public QWidget {
+	Q_OBJECT
+
 public:
 	Spectrogram();
 	~Spectrogram();
 
+public slots:
+	void setFFTSize(int size);
+
 protected:
 	void paintEvent(QPaintEvent *event);
 
+
 private:
 	InputSource *inputSource;
 };
\ No newline at end of file
diff --git a/spectrogramcontrols.cpp b/spectrogramcontrols.cpp
new file mode 100644
index 0000000..53c653b
--- /dev/null
+++ b/spectrogramcontrols.cpp
@@ -0,0 +1,23 @@
+#include "spectrogramcontrols.h"
+#include <QLabel>
+
+SpectrogramControls::SpectrogramControls(const QString & title, QWidget * parent)
+	: QDockWidget::QDockWidget(title, parent)
+{
+	QWidget *widget = new QWidget;
+	fftSizeSlider = new QSlider(Qt::Horizontal);
+	fftSizeSlider->setRange(7, 13);
+	fftSizeSlider->setValue(10);
+
+	layout = new QFormLayout;
+	layout->addRow(new QLabel(tr("FFT size:")), fftSizeSlider);
+	widget->setLayout(layout);
+	setWidget(widget);
+
+	connect(fftSizeSlider, SIGNAL(valueChanged(int)), this, SLOT(fftSizeSliderChanged(int)));
+}
+
+void SpectrogramControls::fftSizeSliderChanged(int size)
+{
+	emit fftSizeChanged((int)pow(2, size));
+}
\ No newline at end of file
diff --git a/spectrogramcontrols.h b/spectrogramcontrols.h
new file mode 100644
index 0000000..9266620
--- /dev/null
+++ b/spectrogramcontrols.h
@@ -0,0 +1,23 @@
+#pragma once
+
+#include <QDockWidget>
+#include <QFormLayout>
+#include <QSlider>
+
+class SpectrogramControls : public QDockWidget {
+	Q_OBJECT
+
+public:
+	SpectrogramControls(const QString & title, QWidget * parent);
+
+signals:
+	void fftSizeChanged(int size);
+
+private slots:
+	void fftSizeSliderChanged(int size);
+
+private:
+	QWidget *widget;
+	QFormLayout *layout;
+	QSlider *fftSizeSlider;
+};
\ No newline at end of file