[winswitch] Start Xpra client in shaded mode or iconified

[Kevin Liagre]

Hello Xpra users,

 I'm using Xpra 0.14.21 and I'm looking for a way to start a client in
shaded or iconified mode.

Currently I'm using xtoolwait to wait until my window is available and then
wmctrl to shade it.
This workaround is working but we see breefly the window appearing and
disappearing.

Any ideas to make it possible with Xpra ?

Thanks