解决自定义控件不透明的方法。Istruggledforageswiththeproblemofhavingcontrolsshowthroughacontrolthatwaspaintedontopofthem.ItseemsthatControlStyles.SupportsTransparentBackColorjustallowedthecontroltopickupthecontainer'sbackgroundcolour/imageandwouldn'tpreventthecontrolfromhidinganycontrolsthatw