bug#25542: 25.1; Restoring the frame from fullscreen to maximized

[martin rudalics]

> I've just downloaded a native w32 build [1] and I've run it on my
> system (MS Windows 10 Enterprise). I see the same problem with this
> native build.

Can you please run under gdb with a breakpoint in w32fullscreen_hook of
w32term.c suitably in here

      else if (f->want_fullscreen == FULLSCREEN_MAXIMIZED)
        {
          if (prev_fsmode == FULLSCREEN_BOTH || prev_fsmode == FULLSCREEN_WIDTH
              || prev_fsmode == FULLSCREEN_HEIGHT)
            /* Make window normal since otherwise the subsequent
               maximization might fail in some cases.  */
            ShowWindow (hwnd, SW_SHOWNORMAL);
          ShowWindow (hwnd, SW_MAXIMIZE);
        }

and tell us how the frame appears immediately after the ShowWindow
calls.  Here the first call makes the frame appear with its "normal"
size, the second one makes it appear maximized.

Thank you, martin