bug#26682: 26.0.50; Error at startup with minibuffer-only frame

[martin rudalics]

> On Windows, however, even
> with my patch, one out of ten times starting Emacs with Stefan's command
> line hangs it with the initial frame visible and I have to quit with
> C-g.
>
> More precisely, it hangs in ‘frame-notice-user-settings’ in the while
> loop below
>
>          ;; MS-Windows needs this to avoid inflooping below.
>          (if (eq system-type 'windows-nt)
>          (sit-for 0 t))
>          ;; If the frame isn't visible yet, wait till it is.
>          ;; If the user has to position the window,
>          ;; Emacs doesn't know its real position until
>          ;; the frame is seen to be visible.
>          (while (not (cdr (assq 'visibility
>                     (frame-parameters frame-initial-frame))))
>            (sleep-for 1))
>
> and it does so always when I run Emacs under GDB.  I don't yet know why
> it hangs: The request to make the frame visible is posted orderly but
> somehow SET_FRAME_VISIBLE gets never executed.  Can you reproduce it?

FYI it's caused by WM_MOVE which OT1H is likely counted by the

    for (count = input_signal_count + 10;
         input_signal_count < count && !FRAME_VISIBLE_P (f);)

loop in x_make_frame_visible and OTOH lacks a SET_FRAME_VISIBLE (f, 1).

martin