void PlotWidget_MotionNotifyEvent(object o, MotionNotifyEventArgs args)
{
int X, Y;
Gdk.ModifierType state;
// Ensure PlotSurface has keyboard focus
DrawingArea da = (DrawingArea)o;
if (!da.HasFocus)
{
da.GrabFocus();
}
args.Event.Window.GetPointer(out X, out Y, out state);
Modifier keys = MouseInput(state);
this.InteractivePlotSurface2D.DoMouseMove(X, Y, keys);
}