diff --git a/src/Input/FGMouseInput.cxx b/src/Input/FGMouseInput.cxx
index 2f7b31de9..af22b3929 100644
--- a/src/Input/FGMouseInput.cxx
+++ b/src/Input/FGMouseInput.cxx
@@ -272,7 +272,11 @@ public:
         FGMouseCursor::Cursor cur = FGMouseCursor::CURSOR_CLOSED_HAND;
 
         osg::Vec2d windowPos;
-        flightgear::eventToWindowCoords(ea, windowPos.x(), windowPos.y());
+        const bool ok = flightgear::eventToWindowCoords(ea, windowPos.x(), windowPos.y());
+        if (!ok) {
+            SG_LOG(SG_GUI, SG_WARN, "doMouseMoveWithCallbacks: ignoring mouse move with missing context/traits");
+            return;
+        }
 
         SGSceneryPicks pickList = globals->get_renderer()->pick(windowPos);
         if(pickList.empty())
@@ -557,7 +561,11 @@ void FGMouseInput::doMouseClick (int b, int updown, int x, int y, bool mainWindo
   // them consumes the event.
 
   osg::Vec2d windowPos;
-  flightgear::eventToWindowCoords(ea, windowPos.x(), windowPos.y());
+  bool ok = flightgear::eventToWindowCoords(ea, windowPos.x(), windowPos.y());
+  if (!ok) {
+      SG_LOG(SG_GUI, SG_WARN, "Ignoring mouse click with null context/traits");
+      return;
+  }
 
   SGSceneryPicks pickList;
 
diff --git a/src/Viewer/FGEventHandler.cxx b/src/Viewer/FGEventHandler.cxx
index 54f03f986..c9f5db121 100644
--- a/src/Viewer/FGEventHandler.cxx
+++ b/src/Viewer/FGEventHandler.cxx
@@ -466,11 +466,15 @@ void FGEventHandler::handleStats(osgGA::GUIActionAdapter& us)
     }
 }
 
-void eventToWindowCoords(const osgGA::GUIEventAdapter* ea,
+bool eventToWindowCoords(const osgGA::GUIEventAdapter* ea,
                          double& x, double& y)
 {
     using namespace osg;
     const GraphicsContext* gc = ea->getGraphicsContext();
+    if (!gc || !gc->getTraits()) {
+        return false;
+    }
+
     const GraphicsContext::Traits* traits = gc->getTraits() ;
     // Scale x, y to the dimensions of the window
     x = (((ea->getX() - ea->getXmin()) / (ea->getXmax() - ea->getXmin()))
@@ -479,23 +483,8 @@ void eventToWindowCoords(const osgGA::GUIEventAdapter* ea,
          * (double)traits->height);
     if (ea->getMouseYOrientation() == osgGA::GUIEventAdapter::Y_INCREASING_DOWNWARDS)
         y = (double)traits->height - y;
+
+    return true;
 }
 
-#if 0
-void eventToWindowCoordsYDown(const osgGA::GUIEventAdapter* ea,
-                              double& x, double& y)
-{
-    using namespace osg;
-    const GraphicsContext* gc = ea->getGraphicsContext();
-    const GraphicsContext::Traits* traits = gc->getTraits() ;
-    // Scale x, y to the dimensions of the window
-    x = (((ea->getX() - ea->getXmin()) / (ea->getXmax() - ea->getXmin()))
-         * (double)traits->width);
-    y = (((ea->getY() - ea->getYmin()) / (ea->getYmax() - ea->getYmin()))
-         * (double)traits->height);
-    if (ea->getMouseYOrientation() == osgGA::GUIEventAdapter::Y_INCREASING_UPWARDS)
-        y = (double)traits->height - y;
-}
-#endif
-    
 }
diff --git a/src/Viewer/FGEventHandler.hxx b/src/Viewer/FGEventHandler.hxx
index d40fffb89..9e1bbbb24 100644
--- a/src/Viewer/FGEventHandler.hxx
+++ b/src/Viewer/FGEventHandler.hxx
@@ -124,8 +124,6 @@ protected:
     SGPropertyNode_ptr _display, _print;
 };
 
-void eventToWindowCoords(const osgGA::GUIEventAdapter* ea, double& x, double& y);
-void eventToWindowCoordsYDown(const osgGA::GUIEventAdapter* ea,
-                              double& x, double& y);
+bool eventToWindowCoords(const osgGA::GUIEventAdapter* ea, double& x, double& y);
 }
 #endif