diff --git a/scalepicker.cpp b/scalepicker.cpp
--- a/scalepicker.cpp
+++ b/scalepicker.cpp
@@ -19,9 +19,9 @@
 
 #include <QEvent>
 #include <QMouseEvent>
+#include <QPainter>
 #include <qwt_scale_widget.h>
 #include <qwt_scale_map.h>
-#include <QtDebug>
 #include <math.h>
 
 #include "scalepicker.h"
@@ -29,11 +29,35 @@
 // minimum size for pick (in pixels)
 #define MIN_PICK_SIZE (2)
 
-ScalePicker::ScalePicker(QwtScaleWidget* scaleWidget) :
+class ScalePickerOverlay : public QwtWidgetOverlay
+{
+public:
+    ScalePickerOverlay(QWidget* widget, ScalePicker* picker);
+
+protected:
+    virtual void drawOverlay(QPainter*) const;
+
+private:
+    ScalePicker* _picker;
+};
+
+ScalePickerOverlay::ScalePickerOverlay(QWidget* widget, ScalePicker* picker) :
+    QwtWidgetOverlay(widget)
+{
+    _picker = picker;
+}
+
+void ScalePickerOverlay::drawOverlay(QPainter* painter) const
+{
+    _picker->drawOverlay(painter);
+}
+
+ScalePicker::ScalePicker(QwtScaleWidget* scaleWidget, QWidget* canvas) :
     QObject(scaleWidget)
 {
     scaleWidget->installEventFilter(this);
     _scaleWidget = scaleWidget;
+    pickerOverlay = new ScalePickerOverlay(canvas, this);
     started = false;
     pressed = false;
 }
@@ -47,6 +71,7 @@ bool ScalePicker::eventFilter(QObject* o
         QMouseEvent* mouseEvent = (QMouseEvent*) event;
         double pos = this->position(mouseEvent);
         double posPx = this->positionPx(mouseEvent);
+        currentPosPx = posPx;
 
         if (event->type() == QEvent::MouseButtonPress &&
             mouseEvent->button() == Qt::LeftButton)
@@ -62,11 +87,12 @@ bool ScalePicker::eventFilter(QObject* o
             if (!started && pressed && (fabs(posPx-firstPosPx) > MIN_PICK_SIZE))
             {
                 started = true;
-                qDebug() << "Pick started:" << firstPos;
+                // pickerOverlay->updateOverlay();
                 emit pickStarted(pos);
             }
             else if (started)
             {
+                pickerOverlay->updateOverlay();
                 emit picking(firstPos, pos);
             }
         }
@@ -77,7 +103,6 @@ bool ScalePicker::eventFilter(QObject* o
                 // finalize
                 started = false;
                 pressed = false;
-                qDebug() << "Picked:" << firstPos << pos;
                 emit picked(firstPos, pos);
             }
         }
@@ -89,6 +114,26 @@ bool ScalePicker::eventFilter(QObject* o
     }
 }
 
+void ScalePicker::drawOverlay(QPainter* painter)
+{
+    if (started)
+    {
+        QRect rect;
+        if (_scaleWidget->alignment() == QwtScaleDraw::BottomScale ||
+            _scaleWidget->alignment() == QwtScaleDraw::TopScale)
+        {
+            int height = painter->device()->height();
+            rect = QRect(firstPosPx, 0, (currentPosPx-firstPosPx), height);
+        }
+        else // vertical
+        {
+            int width = painter->device()->width();
+            rect = QRect(0, firstPosPx, width, (currentPosPx-firstPosPx));
+        }
+        painter->drawRect(rect);
+    }
+}
+
 double ScalePicker::position(QMouseEvent* mouseEvent)
 {
     double pos;
diff --git a/scalepicker.h b/scalepicker.h
--- a/scalepicker.h
+++ b/scalepicker.h
@@ -22,17 +22,19 @@
 
 #include <QObject>
 #include <QMouseEvent>
-#include <QPointF>
 #include <qwt_scale_widget.h>
+#include <qwt_widget_overlay.h>
 
 class ScalePicker : public QObject
 {
     Q_OBJECT
 
 public:
-    ScalePicker(QwtScaleWidget* scaleWidget);
+    ScalePicker(QwtScaleWidget* scaleWidget, QWidget* canvas);
     virtual bool eventFilter(QObject*, QEvent*);
 
+    void drawOverlay(QPainter*); // called from ScalePickerOverlay
+
 signals:
     void pickStarted(double pos);
     void picking(double firstPos, double lastPos);
@@ -40,6 +42,7 @@ signals:
 
 private:
     QwtScaleWidget* _scaleWidget;
+    QwtWidgetOverlay* pickerOverlay; // ScalePickerOverlay
     double position(QMouseEvent*); // returns the axis mouse position relative to plot coordinates
     double positionPx(QMouseEvent*); // returns the axis mouse position in pixels
 
@@ -47,6 +50,7 @@ private:
     bool started;
     double firstPos; // converted to plot coordinates
     double firstPosPx; // pixel coordinates
+    double currentPosPx; // current position in pixel coordinates
 };
 
 #endif // SCALEPICKER_H
diff --git a/scalezoomer.cpp b/scalezoomer.cpp
--- a/scalezoomer.cpp
+++ b/scalezoomer.cpp
@@ -18,45 +18,20 @@
 */
 
 #include <QRectF>
-#include <QtDebug>
+
 #include "scalezoomer.h"
 
 ScaleZoomer::ScaleZoomer(QwtPlot* plot, QwtPlotZoomer* zoomer) :
     QObject(plot),
-    bottomPicker(plot->axisWidget(QwtPlot::xBottom)),
-    leftPicker(plot->axisWidget(QwtPlot::yLeft))
+    bottomPicker(plot->axisWidget(QwtPlot::xBottom), plot->canvas()),
+    leftPicker(plot->axisWidget(QwtPlot::yLeft), plot->canvas())
 {
     _plot = plot;
     _zoomer = zoomer;
-    connect(&bottomPicker, &ScalePicker::pickStarted, this, &ScaleZoomer::bottomPickStarted);
-    connect(&bottomPicker, &ScalePicker::picking, this, &ScaleZoomer::bottomPicking);
     connect(&bottomPicker, &ScalePicker::picked, this, &ScaleZoomer::bottomPicked);
     connect(&leftPicker, &ScalePicker::picked, this, &ScaleZoomer::leftPicked);
 }
 
-void ScaleZoomer::bottomPickStarted(double firstPos)
-{
-    double yMin = _plot->axisScaleDiv(QwtPlot::yLeft).lowerBound();
-    double yMax = _plot->axisScaleDiv(QwtPlot::yLeft).upperBound();
-    rectShape.setRect(QRectF(firstPos, yMin, 2, yMax-yMin));
-    rectShape.attach(_plot);
-    _plot->replot();
-}
-
-void ScaleZoomer::bottomPicking(double firstPos, double lastPos)
-{
-    double yMin = _plot->axisScaleDiv(QwtPlot::yLeft).lowerBound();
-    double yMax = _plot->axisScaleDiv(QwtPlot::yLeft).upperBound();
-    if (lastPos > firstPos) {
-        rectShape.setRect(QRectF(firstPos, yMin, lastPos-firstPos, yMax-yMin));
-    }
-    else
-    {
-        rectShape.setRect(QRectF(lastPos, yMin, firstPos-lastPos, yMax-yMin));
-    }
-    _plot->replot();
-}
-
 void ScaleZoomer::bottomPicked(double firstPos, double lastPos)
 {
     QRectF zRect;
@@ -74,8 +49,6 @@ void ScaleZoomer::bottomPicked(double fi
     zRect.setBottom(_plot->axisScaleDiv(QwtPlot::yLeft).lowerBound());
     zRect.setTop(_plot->axisScaleDiv(QwtPlot::yLeft).upperBound());
     _zoomer->zoom(zRect);
-    rectShape.detach();
-    _plot->replot();
 }
 
 void ScaleZoomer::leftPicked(double firstPos, double lastPos)
diff --git a/scalezoomer.h b/scalezoomer.h
--- a/scalezoomer.h
+++ b/scalezoomer.h
@@ -23,7 +23,6 @@
 #include <QObject>
 #include <qwt_plot.h>
 #include <qwt_plot_zoomer.h>
-#include <qwt_plot_shapeitem.h>
 
 #include "scalepicker.h"
 
@@ -40,12 +39,8 @@ private:
     ScalePicker bottomPicker;
     ScalePicker leftPicker;
 
-    QwtPlotShapeItem rectShape;
-
 private slots:
-    void bottomPickStarted(double firstPos);
     void bottomPicked(double firstPos, double lastPos);
-    void bottomPicking(double firstPos, double lastPos);
     void leftPicked(double firstPos, double lastPos);
 };