MDIExtender Control - Version 1.0 This unique control allows developers to use MDI Child Forms in ActiveX DLL's for the first time. This Visual Basic limitation is overcome by simply inserting the MDIExtender Control on Form into the ActiveX DLL. This form will behave the same as a normal Visual Basic MDI Child Form. No code is required to active control’s functionality. The MDIExtender Control is lightweight, about 100 KB, and there are no dependencies. MDIExtender Control can be used with Visual Basic Ver. 5 and 6.