As described above, container controls are ActiveX controls that visually contain other controls. The ActiveX controls architecture specifies the ISimpleFrameSite interface to enable container controls. Containers may also support container controls without supporting ISimpleFrameSite, although the behavior cannot be guaranteed. For this reason, a component category exists for SimpleFrameSite controls where the full functionality of this interface is required.
To support container controls without implementing ISimpleFrameSite, an ActiveX control container must:
- Activate all controls at all times.
- Reparent the contained controls to the hWnd of the containing control.
- Remain the parent of the container control.