PRB: ActiveX Control Painting Problems in Visual C++ 4.2

The ActiveX (OLE) Control may not paint correctly if it was built using Visual C++ 4.2. Two known issues include controls not repainting when resized, and control child windows not being repainted. Other painting problems have been observed when subclassing native Windows controls.

This behavior is caused by changes to COleControl::OnPaint which add optimizations to improve performance.

COleControl now includes a method, GetControlFlags, to control how painting will be handled in an ActiveX control. Removing the fastBeginPaint flag from the bit field returned by GetControlFlags will cause your ActiveX control to use the same OnPaint code found in Visual C++ 4.1

This behavior is by design.

DWORD CMyOleControl::GetControlFlags ()
{
   return COleControl::GetControlFlags() & ~fastBeginPaint;
}
				

For an explanation of the GetControlFlags return values, see the documentation in Books on Line.