Select a window interactively, and return the specified window. Use a special cursor and let the user click to select the window. The optional CURSOR argument can be either a cursor object or #t to indicate to use the "skull and cross-bones" kill cursor (recommended for destructive operations like delete-window and destroy-window). The optional argument RELEASE? indicates whether to wait for a mouse release or act immediately on the click. Returns #f if no window was selected.