[winswitch] First time install of xpra: black screen in all windows.

[G.W. Haywood]

Hi there,

My first use of xpra, for which (I think:) I'm very grateful, and my
first post to this list.

I built version 4.3 from source (git clone) on two machines.  One is a
laptop (Debian Buster, Intel i7) and the other is a Raspberry Pi 3B+
(Raspbian Bullseye, ARM):

8<----------------------------------------------------------------------
ged at piplus:~$ uname -a
Linux piplus 5.10.60-v7+ #1449 SMP Wed Aug 25 15:00:01 BST 2021 armv7l GNU/Linux
ged at piplus:~$ xpra --version
xpra v4.3-r29977 (g8a0d2b663)
ged at piplus:~$ ssh laptop3
Linux laptop3 4.19.0-17-amd64 #1 SMP Debian 4.19.194-3 (2021-07-18) x86_64
...
laptop3:~$ >>> xpra --version
xpra v4.3-r867
8<----------------------------------------------------------------------

I can start an xpra server on the laptop e.g. with DISPLAY=:101, then
start an xterm for that instance, then attach a local xpra client to
display 101 on the laptop and everything is fine.  However if I attach
to the same server from a client on the Pi, I see a window but there's
no content displayed in it - it's completely black.  Apart from that
it's a functioning connection.  I can run commands in the black window
(blindfold), and they are executed and saved in the command history.
Also, if on the laptop I start the browser (palemoon) for display 101,
and attach to display 101 from an xpra client on the Pi, three windows
are opened on the Pi because I normally run with three windows for
various different jobs that I'm working on in the browser.  The window
titles are correctly displayed in the window borders on the Pi, but
like the xterm window, the content is completely black.

If there are bits of logs somewhere which might be helpful in tracking
down the problem please let me know what to look for.  I've searched
the list archive but found nothing which quite matched these symptoms.

-- 

73,
Ged.