race between window menu rendering and DOM API window measurements
May have already reported this earlier...
The first call of gui_canvas_get_scroll to a newly opened patch or subpatch will return a window height that doesn't take into account the space eaten by the nw.js window menubar. Thus the returned height is too large, and when the menubar gets rendered an unnecessary scrollbar appears.
Ideally we would send a do_getscroll first and then wait 250ms in the simple throttling algorithm of gui_canvas_get_scroll. That would result in a more responsive UX-- as it is the 250ms makes the initial window rendering appear sluggish. But that means fixing the race between menubar rendering and DOM API measurement, or finding some workaround for it.