gui_toolkit 0.88.0

Fixed

• Text in a dialog or a popover can be selected: their panel took every press, so a plain .Selectable label in it selected nothing, showed no text cursor, and a label made .Clickable to get the press counted as a button. The panel is now .Press_Stop (new Box_Flag: clickable only so that what is under it gets no press): a press on it is a press on nothing, selectable text in it takes its own, and a selection stays on the surface it started on, whatever is built behind it.