diff --git a/plot.cpp b/plot.cpp
--- a/plot.cpp
+++ b/plot.cpp
@@ -98,6 +98,7 @@ void Plot::darkBackground(bool enabled)
         grid.setPen(Qt::darkGray);
         zoomer.setRubberBandPen(QPen(Qt::white));
         zoomer.setTrackerPen(QPen(Qt::white));
+        sZoomer.setPickerPen(QPen(Qt::white));
     }
     else
     {
@@ -105,6 +106,7 @@ void Plot::darkBackground(bool enabled)
         grid.setPen(Qt::lightGray);
         zoomer.setRubberBandPen(QPen(Qt::black));
         zoomer.setTrackerPen(QPen(Qt::black));
+        sZoomer.setPickerPen(QPen(Qt::black));
     }
     replot();
 }
diff --git a/scalepicker.cpp b/scalepicker.cpp
--- a/scalepicker.cpp
+++ b/scalepicker.cpp
@@ -130,10 +130,17 @@ void ScalePicker::drawOverlay(QPainter* 
             int width = painter->device()->width();
             rect = QRect(0, firstPosPx, width, (currentPosPx-firstPosPx));
         }
+
+        painter->setPen(_pen);
         painter->drawRect(rect);
     }
 }
 
+void ScalePicker::setPen(QPen pen)
+{
+    _pen = pen;
+}
+
 double ScalePicker::position(QMouseEvent* mouseEvent)
 {
     double pos;
diff --git a/scalepicker.h b/scalepicker.h
--- a/scalepicker.h
+++ b/scalepicker.h
@@ -22,6 +22,7 @@
 
 #include <QObject>
 #include <QMouseEvent>
+#include <QPen>
 #include <qwt_scale_widget.h>
 #include <qwt_widget_overlay.h>
 
@@ -34,6 +35,7 @@ public:
     virtual bool eventFilter(QObject*, QEvent*);
 
     void drawOverlay(QPainter*); // called from ScalePickerOverlay
+    void setPen(QPen pen);
 
 signals:
     void pickStarted(double pos);
@@ -43,14 +45,16 @@ 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
+    QPen _pen;
 
     bool pressed;
     bool started;
     double firstPos; // converted to plot coordinates
     double firstPosPx; // pixel coordinates
     double currentPosPx; // current position in pixel coordinates
+
+    double position(QMouseEvent*); // returns the axis mouse position relative to plot coordinates
+    double positionPx(QMouseEvent*); // returns the axis mouse position in pixels
 };
 
 #endif // SCALEPICKER_H
diff --git a/scalezoomer.cpp b/scalezoomer.cpp
--- a/scalezoomer.cpp
+++ b/scalezoomer.cpp
@@ -32,6 +32,12 @@ ScaleZoomer::ScaleZoomer(QwtPlot* plot, 
     connect(&leftPicker, &ScalePicker::picked, this, &ScaleZoomer::leftPicked);
 }
 
+void ScaleZoomer::setPickerPen(QPen pen)
+{
+    bottomPicker.setPen(pen);
+    leftPicker.setPen(pen);
+}
+
 void ScaleZoomer::bottomPicked(double firstPos, double lastPos)
 {
     QRectF zRect;
diff --git a/scalezoomer.h b/scalezoomer.h
--- a/scalezoomer.h
+++ b/scalezoomer.h
@@ -21,6 +21,7 @@
 #define SCALEZOOMER_H
 
 #include <QObject>
+#include <QPen>
 #include <qwt_plot.h>
 #include <qwt_plot_zoomer.h>
 
@@ -32,6 +33,7 @@ class ScaleZoomer : public QObject
 
 public:
     ScaleZoomer(QwtPlot*, QwtPlotZoomer*);
+    void setPickerPen(QPen pen);
 
 private:
     QwtPlot* _plot;