I have a custom gadget that I add to a window (created by the Window Class). The gadget needs to erase its background before it gets GM_RENDERed. It appears to me (based on experimenting) that the window class uses FORESHINEPEN (rather than BACKGROUNDPEN) for the background.
Is it really the case? Can I rely on this pen being used across various themes? I mean, will FORESHINEPEN (whatever colour it represents in a particular theme) always be used for the background?