In previous 4.8 versions, the panel started extremely fast on login: By far less than a second, before any other application (I'm on a fast machine). In today's git version, the panel takes about 5 seconds to appear at login, long after any other application started automatically at login. Moreover, there is a message in .xsession-errors which has not been there in old versions: "xfce4-panel: No window manager registered on screen 0. To start the panel without this check, run with --disable-wm-check."
And the window manager is running? It should wait for the window manager to appear, if it does the panel is directly started (so we don't switch compositing twice).
Do you use xfwm4?
Yep, both the old and the new times are with a standard xfwm4 setup: Things are started by xfce4-session, including xfwm4.
Just tried again: There are more than 3 seconds between the terminal window appearing (including title bar, hence xfwm is already running) and the panels coming up. Also, pids suggest that xfwm is started shortly before the panel: xfwm 12646, then comes Thunar, then the panel (12651). However, there are *ages* between the panel and the panel plugins: Panel start time 16:02:07, and the plugins are started at 16:02:13, beginning at pid 12703. What is the interval for the window manager check in the panel? (I mean, if the first check fails as the message shows, how long does the panel wait before it tries again?)
The check is running every 50ms for 5 seconds (before it starts anyway), looking for the _NET_WM_CM_S0 atom (wm in screen 0).
So obviously we have the "starts anyway" case. But what makes the check fail? It worked in 4.8 release. Is there anything I can test easily?
Mmm it depends on compositing enabled or not.
Fixed in e3e6be1.
I had compositing compiled in but turned off. Unfortunately, I can't test any more: Current git (as provided by Gentoo -9999 ebuilds) doesn't compile for me, I'm back at the released versions.