This is a severe problem, and I am experiencing it this the upgrade from Xubuntu 13.10 to 14.04 at the start of may.
I use an up-to-date Xubuntu 14.04:
$ xfwm4 --version
This is xfwm4 version 4.11.1 (revision 2b800f4) for Xfce 4.10
Released under the terms of the GNU General Public License.
Compiled against GTK+-2.24.23, using GTK+-2.24.23.
Build configuration and supported features:
- Startup notification support: Yes
- XSync support: Yes
- Render support: Yes
- Xrandr support: Yes
- Embedded compositor: Yes
- KDE systray proxy (deprecated): No
I use a 64 bits system. Kernel is currently : 3.13.0-30-generic. I use the "radeon" video driver. lspci says :
VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Cedar [Radeon HD 5000/6000/7350/8350 Series]
I have one panel configured. With a workspace switcher plugin. I usually configure two workspaces.
After a few hours (it varies a lot) using my system, suddenly, all the windows are "undrawn" from my display, the clock on my panel displays an hour far back in time (several hours). So I see my panel and the desktop background.
If I switch workspace (keyboard shortcut, or clicking the workspace panel plugin), everything comes back to normal. And re-disappear at a random pace (can be quite high actually).
The only way I found to prevent this behavior is to configure only one workspace.
I am not even sure this is an Xfce problem. I wish I could help more but I really don't know what or where to look for. You guys can ask me anything, I'd do my best to help investigate this annoying problem.