diff --git a/src/scrollbar.cpp b/src/scrollbar.cpp
new file mode 100644
--- /dev/null
+++ b/src/scrollbar.cpp
@@ -0,0 +1,170 @@
+#include <qstyle.h>
+#include <qstyleoption.h>
+#include "scrollbar.h"
+
+ScrollBar::ScrollBar( QWidget * parent ):
+    QScrollBar( parent )
+{
+    init();
+}
+
+ScrollBar::ScrollBar( Qt::Orientation o,
+        QWidget *parent ):
+    QScrollBar( o, parent )
+{
+    init();
+}
+
+ScrollBar::ScrollBar( double minBase, double maxBase,
+        Qt::Orientation o, QWidget *parent ):
+    QScrollBar( o, parent )
+{
+    init();
+    setBase( minBase, maxBase );
+    moveSlider( minBase, maxBase );
+}
+
+void ScrollBar::init()
+{
+    d_inverted = orientation() == Qt::Vertical;
+    d_baseTicks = 1000000;
+    d_minBase = 0.0;
+    d_maxBase = 1.0;
+    moveSlider( d_minBase, d_maxBase );
+
+    connect( this, SIGNAL( sliderMoved( int ) ), SLOT( catchSliderMoved( int ) ) );
+    connect( this, SIGNAL( valueChanged( int ) ), SLOT( catchValueChanged( int ) ) );
+}
+
+void ScrollBar::setInverted( bool inverted )
+{
+    if ( d_inverted != inverted )
+    {
+        d_inverted = inverted;
+        moveSlider( minSliderValue(), maxSliderValue() );
+    }
+}
+
+bool ScrollBar::isInverted() const
+{
+    return d_inverted;
+}
+
+void ScrollBar::setBase( double min, double max )
+{
+    if ( min != d_minBase || max != d_maxBase )
+    {
+        d_minBase = min;
+        d_maxBase = max;
+
+        moveSlider( minSliderValue(), maxSliderValue() );
+    }
+}
+
+void ScrollBar::moveSlider( double min, double max )
+{
+    const int sliderTicks = qRound( ( max - min ) /
+        ( d_maxBase - d_minBase ) * d_baseTicks );
+
+    // setRange initiates a valueChanged of the scrollbars
+    // in some situations. So we block
+    // and unblock the signals.
+
+    blockSignals( true );
+
+    setRange( sliderTicks / 2, d_baseTicks - sliderTicks / 2 );
+    int steps = sliderTicks / 200;
+    if ( steps <= 0 )
+        steps = 1;
+
+    setSingleStep( steps );
+    setPageStep( sliderTicks );
+
+    int tick = mapToTick( min + ( max - min ) / 2 );
+    if ( isInverted() )
+        tick = d_baseTicks - tick;
+
+    setSliderPosition( tick );
+    blockSignals( false );
+}
+
+double ScrollBar::minBaseValue() const
+{
+    return d_minBase;
+}
+
+double ScrollBar::maxBaseValue() const
+{
+    return d_maxBase;
+}
+
+void ScrollBar::sliderRange( int value, double &min, double &max ) const
+{
+    if ( isInverted() )
+        value = d_baseTicks - value;
+
+    const int visibleTicks = pageStep();
+
+    min = mapFromTick( value - visibleTicks / 2 );
+    max = mapFromTick( value + visibleTicks / 2 );
+}
+
+double ScrollBar::minSliderValue() const
+{
+    double min, dummy;
+    sliderRange( value(), min, dummy );
+
+    return min;
+}
+
+double ScrollBar::maxSliderValue() const
+{
+    double max, dummy;
+    sliderRange( value(), dummy, max );
+
+    return max;
+}
+
+int ScrollBar::mapToTick( double v ) const
+{
+    const double pos = ( v - d_minBase ) / ( d_maxBase - d_minBase ) * d_baseTicks;
+    return static_cast<int>( pos );
+}
+
+double ScrollBar::mapFromTick( int tick ) const
+{
+    return d_minBase + ( d_maxBase - d_minBase ) * tick / d_baseTicks;
+}
+
+void ScrollBar::catchValueChanged( int value )
+{
+    double min, max;
+    sliderRange( value, min, max );
+    Q_EMIT valueChanged( orientation(), min, max );
+}
+
+void ScrollBar::catchSliderMoved( int value )
+{
+    double min, max;
+    sliderRange( value, min, max );
+    Q_EMIT sliderMoved( orientation(), min, max );
+}
+
+int ScrollBar::extent() const
+{
+    QStyleOptionSlider opt;
+    opt.init( this );
+    opt.subControls = QStyle::SC_None;
+    opt.activeSubControls = QStyle::SC_None;
+    opt.orientation = orientation();
+    opt.minimum = minimum();
+    opt.maximum = maximum();
+    opt.sliderPosition = sliderPosition();
+    opt.sliderValue = value();
+    opt.singleStep = singleStep();
+    opt.pageStep = pageStep();
+    opt.upsideDown = invertedAppearance();
+    if ( orientation() == Qt::Horizontal )
+        opt.state |= QStyle::State_Horizontal;
+    return style()->pixelMetric( QStyle::PM_ScrollBarExtent, &opt, this );
+}