A vertical panel arranges its subwindows in a single column. See
also panel%.
(make-object vertical-panel% parentstyle)->vertical-panel% object parent : frame%, dialog%, panel%, or pane% object style = null : list of symbols in '(border)
If the 'border style is specified, the window is created with
a thin border (only in this case, the client size of the panel may be
less than its total size).