FilterMouse
virtual void FilterMouse(BPoint* where) const;
virtual void FilterMouse(BPoint* where) const;
fCanvasView->FilterMouse(&where);
fCanvasView->FilterMouse(&where);
fCanvasView->FilterMouse(&where);
fCanvasView->FilterMouse(&where);
fView->FilterMouse(&where);
fView->FilterMouse(&where);