A handy setup for a standard, titled, draggable subwindow (a non-background child of a ZSplit). The top of the subwindow contains a banner with a close button, a title that can be used to drag the window, and a grow button.
Except for some details of the feedback and the handling of keywords, ZChassis could be defined by a macro:
(Macro ZChassis ((Open FALSE)
(At (0.5 0.5))
(Title "<Untitled>")
child)
`(ZChild
(Open ,Open)
(At ,@At)
(Stable
(Border
(VBox
(HBox
(CloseButton "C")
Bar
(Shape (Width + Inf) (ZMove ,Title))
Bar
(ZGrow "G"))
Bar
(Frame ,child))))))