ComboBox: Fix for scrolling over a dropdown.

It doesn't need to propagate the MouseWhile event to the parent.

src/slic3r/GUI/Widgets/ComboBox.cpp

@@ -294,7 +294,6 @@ void ComboBox::mouseDown(wxMouseEvent &event)
 
 void ComboBox::mouseWheelMoved(wxMouseEvent &event)
 {
-    event.Skip();
     if (drop_down) return;
     auto delta = ((event.GetWheelRotation() < 0) == event.IsWheelInverted()) ? -1 : 1;
     unsigned int n = GetSelection() + delta;