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))))))