Overlapping subwindows

The program Overlap.m3 illustrates creating movable and resizable subwindows. Each subwindow is a ZChassisVBT. These ZChassisVBT's must appear inside a ZSplit. The top of the ZChassisVBT is a banner containing a close button, draggable title and a grow button. Several ZChassisVBT's can be seen in figure~\ref{sd:overlap.m3}. Clicking on the close button unmaps the ZChassisVBT causing it to disappear. Clicking on the grow button allows changing the size of ZChassisVBT. Clicking on the title and dragging moves the ZChassisVBT inside its ZSplit parent.

A ZChassisVBT can be created by a call of the form: 

NEW(ZChassisVBT.T).init(ch, title, shadow, closable, open)
where ch and title are VBT's. The close button will be displayed only if the argument closable is set to TRUE. The appearance of the buttons are governed by the given shadow. If the argument open is set to TRUE, then the ZChassisVBT will be mapped when it is inserted as a child of the ZSplit parent. Other arguments govern the relative placement of the ZChassisVBT.