Bug 309102

Sometimes when switching between apps or clicking "Show the Desktop". Some applications that were previously in the taskbar will disappear from the taskbar.

Pressing Alt+Tab, the applications can be brought to the front, minimized, maximized, etc. but the application is still missing from the taskbar.  


"Only show tasks from this activity" is the default and the only option enabled in my Task manager settings.

The only way I've found to make the application reappear on the taskbar is to:
1. Toggle on "Only show tasks that are minimized.
2. Hit apply
3. Toggle off "only show tasks that are minimized.
4. Hit apply again, and all the missing tasks now appear in the taskbar.

Note: Even though the apps have disappeared from the task-bar, I can use alt+tab to cycle between them.

Note: It seems to happen the most when the system is under heavy load.   Loading several apps at the same time or minimizing a lot of applications quickly.  This can trigger some applications to suddenly disappear from the taskbar.


Reproducible: Sometimes

Steps to Reproduce:
Minimizing a lot of applications simultaneously.
Launching a lot of applications simultaneously.
Actual Results:  
Some applications stop being listed on the taskbar or don't ever show up on the taskbar after being launched.

Expected Results:  
All applications should show up on the taskbar.