The problem has occurred occassionally while dropping fields onto a container. Selecting the control or closing and reopening the the class has fixed it. The latest is a container class that has a pageframe and 20 other controls (comboboxes and textboxes). When working on the container class (Line_Info) in design mode the pageframe displays correctly. When I place the container class (Line_Info) onto another container class (Line_PageFrame) the pageframe's ActivePage property is set to 0 and the pageframe is not visible. I have to manually set the ActivePage property of the pageframe to 1 by editing the container class (Line_Info) place on the Line_PageFrame class. Anyone experienced problems with controls not being visible in design mode?
