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

[martin rudalics]

> I don't see this in the current sources.  Is this your local change?

Yes.

> If so, is there a matching implementation for 'undecorated' on X?  Can
> both be added to Emacs?

There is one for X and a separate one for GTK.  All of them work here
but I read that a few X window managers notoriously ignore them.  BTW,
the term "undecorated" is derived from gtk_window_set_decorated - just
that our frames are by default decorated so I had to negate it.

> If there's only an implementation of 'undecorated' for MS-Windows, I
> suggest to adapt it such that the same effect is produced when
> border-width is set to zero.  The border-width parameter is already
> supported on X, so we will have no problem with that.

As mentioned before I process `border-width' specially on Windows - that
is, I produce the one-pixel wide thin-line border if border-width is a
positive number.  X11 allows to specifiy an arbitrary border-width.  So
far I haven't been able to produce any border with GTK.  But I have
added an option to color the internal border which can then be used in a
uniform manner on all frames.

martin