diff --git a/dgl/ImageWidgets.hpp b/dgl/ImageWidgets.hpp
index ac8a3abb..4380d2b3 100644
--- a/dgl/ImageWidgets.hpp
+++ b/dgl/ImageWidgets.hpp
@@ -150,6 +150,7 @@ private:
 
     int  fRotationAngle;
     bool fDragging;
+    bool fRightClicked;
     int  fLastX;
     int  fLastY;
 
diff --git a/dgl/src/ImageWidgets.cpp b/dgl/src/ImageWidgets.cpp
index 94bf58a1..adf220be 100644
--- a/dgl/src/ImageWidgets.cpp
+++ b/dgl/src/ImageWidgets.cpp
@@ -217,6 +217,7 @@ ImageKnob::ImageKnob(Window& parent, const Image& image, Orientation orientation
       fOrientation(orientation),
       fRotationAngle(0),
       fDragging(false),
+      fRightClicked(false),
       fLastX(0),
       fLastY(0),
       fCallback(nullptr),
@@ -245,6 +246,7 @@ ImageKnob::ImageKnob(Widget* widget, const Image& image, Orientation orientation
       fOrientation(orientation),
       fRotationAngle(0),
       fDragging(false),
+      fRightClicked(false),
       fLastX(0),
       fLastY(0),
       fCallback(nullptr),
@@ -273,6 +275,7 @@ ImageKnob::ImageKnob(const ImageKnob& imageKnob)
       fOrientation(imageKnob.fOrientation),
       fRotationAngle(imageKnob.fRotationAngle),
       fDragging(false),
+      fRightClicked(false),
       fLastX(0),
       fLastY(0),
       fCallback(imageKnob.fCallback),
@@ -300,7 +303,8 @@ ImageKnob& ImageKnob::operator=(const ImageKnob& imageKnob)
     fUsingLog      = imageKnob.fUsingLog;
     fOrientation   = imageKnob.fOrientation;
     fRotationAngle = imageKnob.fRotationAngle;
-    fDragging = false;
+    fDragging      = false;
+    fRightClicked  = false;
     fLastX    = 0;
     fLastY    = 0;
     fCallback = imageKnob.fCallback;
@@ -515,9 +519,11 @@ void ImageKnob::onDisplay()
 
 bool ImageKnob::onMouse(const MouseEvent& ev)
 {
-    if (ev.button != 1)
+    if (ev.button > 3 || ev.button < 1)
         return false;
 
+    fRightClicked = (ev.button == 3) ? true : false;
+
     if (ev.press)
     {
         if (! contains(ev.pos))
@@ -563,7 +569,8 @@ bool ImageKnob::onMotion(const MotionEvent& ev)
     {
         if (const int movX = ev.pos.getX() - fLastX)
         {
-            d     = (ev.mod & kModifierControl) ? 2000.0f : 200.0f;
+            d = (ev.mod & kModifierControl) ? 2000.0f : 200.0f;
+                if (fRightClicked) d = d*10.0f;
             value = (fUsingLog ? _invlogscale(fValueTmp) : fValueTmp) + (float(fMaximum - fMinimum) / d * float(movX));
             doVal = true;
         }
@@ -572,7 +579,8 @@ bool ImageKnob::onMotion(const MotionEvent& ev)
     {
         if (const int movY = fLastY - ev.pos.getY())
         {
-            d     = (ev.mod & kModifierControl) ? 2000.0f : 200.0f;
+            d = (ev.mod & kModifierControl) ? 2000.0f : 200.0f;
+                if (fRightClicked) d = d*10.0f;
             value = (fUsingLog ? _invlogscale(fValueTmp) : fValueTmp) + (float(fMaximum - fMinimum) / d * float(movY));
             doVal = true;
         }