bug#25408: Remove Decorations Around Emacs Frame (Windows OS)

[martin rudalics]

> I’ve worked it out: the toolbar is considered a ‘decoration’ by Cocoa,
> so it is automatically removed when I change a frame to undecorated.
> However, when I create a new undecorated frame the frame redrawing
> code waits for the toolbar to be drawn, which will never happen.
>
> I think this gives me two options:
>
>    1. Get Emacs to disable the toolbar when switching to undecorated
>       frames.
>
>    2. Use a different method of removing the titlebar when the toolbar
>       is enabled than when the toolbar is disabled. This option will
>       only work in macOS 10.11 and above.
>
> Option 1 seems preferable to me, although we could add option 2 later.

Agreed.  What happens in an undecorated frame with `tool-bar-mode'
turned off when you turn on `tool-bar-mode'?

> I don’t know enough about NS to be able to answer this. I’ll give it a
> go and see what happens.

Fine.

Thanks, martin