Hello Wine developers, I don't know if you guys are interested in this or not, but I figured I'd let you know that Microsoft has now documented one of the undocumented toolbar messages. include/commctrl.h (Wine) #define TB_UNKWN45D (WM_USER + 93) include\um\commctrl.h (Windows) #define TB_SETBOUNDINGSIZE (WM_USER + 93) TB_SETBOUNDINGSIZE message https://msdn.microsoft.com/en-us/library/ee663584(v=vs.85).aspx << Sets the bounding size for a multi-column toolbar control. >> That would mean you could also make the corresponding changes to this code as well: dlls/comctl32/toolbar.c case TB_UNKWN45D: return TOOLBAR_Unkwn45D(hwnd, wParam, lParam); /* UNDOCUMENTED MESSAGE: This appears to set some kind of size. Perhaps it * is the maximum size of the toolbar? */ static LRESULT TOOLBAR_Unkwn45D(HWND hwnd, WPARAM wParam, LPARAM lParam) Anyway, just figured I'd share that with you guys. Cheers, Alan Feldman