Bug#935896: add support for xrandr hotplug_mode_update property

[Martin <bugs.m1@kkk-web.de>]

Hello Yves.

Thanks for your hints. I just wanted to express that XFCE4 is unusable
in this special situation with SPICE. Bug reports should contain a line
of what the software is expected to do. Perhaps I got the wording wrong
as I'm no native speaker. I know FOSS is often maintained in free time
and appreciate that.

Nevertheless I would classify this behaviour as "bug", not "wishlist".
I will file a bug in the xfce bugtracker.

If this would be fixed in XFCE4 upstream, will it get into buster as a
fixup?

Regards,
Martin