I did a quick check of ToolbarMessages that cause WM_PAINT instantly:
TB_CHANGEBITMAP TB_CHECKBUTTON TB_DELETEBUTTON TB_ENABLEBUTTON TB_INDERTERMINATE TB_MARKBUTTON TB_PRESSBUTTON TB_SETBITMAPSIZE TB_SETBUTTONSIZE TB_SETBUTTONWIDTH TB_SETCOLOSCHEME TB_SETIMAGELIST TB_SETINDENT TB_SETINSERTMARK TB_SETMAXTEXTROWS TB_SETSTATE
I left some the remaining ToolbarMessages untestet because i did not know how to send them correcty with controlspy.
other Messages showing up and caused Paint: WM_UNKNOWN(128) WM_CHILDACTIVATE WM_ERASEBKGND WM_MOUSELEAVE(borders)
probably this is not everything you need. (:
Tho