I'm using last version of xpra in Arch Linux and I get random black backgrounds for the forwarded systray icons. This happens usually only to some icons, when a new icon appears or right from the start of the client. I'm unable to figure out a pattern here.
Please specify what exact version you have. (unlikely to be trunk) What desktop environment, what command lines, what example applications we can use to reproduce, etc. See wiki/ReportingBugs
Version: xpra v1.0.4-r15266 DE: Xfce
I see black background for Pidgin, Blink, Deluge, Thunderbird with Firetray extension.
This problem doesn't seem to be occurring in the 2.x version anymore.
There are no differences between 1.x and 2.x when it comes to the systray code on Linux (there were changes for MS Windows clients only). So the "fix" is unlikely to have come from xpra, maybe another of your system libraries got updated?
this ticket has been moved to: https://github.com/Xpra-org/xpra/issues/1466