Skip the slider event to allow the stepping to work

The stepping is in a static event handler, so it is called
after the dynamic handler and so the dynamic handler must
allow the event to continue processing.

Fixes https://gitlab.com/kicad/code/kicad/issues/5319

common/dialogs/panel_common_settings.cpp

@@ -174,6 +174,7 @@ bool PANEL_COMMON_SETTINGS::TransferDataFromWindow()
 void PANEL_COMMON_SETTINGS::OnScaleSlider( wxScrollEvent& aEvent )
 {
     m_iconScaleAuto->SetValue( false );
+    aEvent.Skip();
 }