workspace switcher applet crashes window manager
| Affects | Status | Importance | Assigned to | Milestone | |
|---|---|---|---|---|---|
| gnome-panel (Ubuntu) |
Invalid
|
Undecided
|
Unassigned | ||
Bug Description
Ubuntu 10.04.1 LTS - gnome, using metacity (no effects). Bug occurs on two dell laptops, and several desktop machines, dell and others.
To reproduce:
1) Turn off visual effects (System -> preferences -> appearance -> visual effects -> "None")
2) start gconf-editor; set apps -> metacity -> general -> num_workspaces to 17
3) right click on title bar of any window.
Analysis:
workspace switcher preferences widget allows you to specify number of workspaces (can also do this via gconf-editor -> apps -> metacity -> general -> num_workspaces). However, it appears that there is *now* software that depends on a hard-wired limit of 16 workspaces (limitation inherited from compiz).
under the workspace switcher preferences widget, if you increase the number of workspaces to 17, an additional workspace name is created ("Workspace 17"). (in the past, there was no limit on the number of workspaces except what would fit in the panel.)
now, under gconf-editor -> apps -> metacity -> workspace_names there are 16 variable names, name_1 through name_16. if you change gconf-editor -> apps -> metacity -> general -> num_workspaces to 17, no additional workspace name variable is created.
After setting num_workspaces to 17, if you right click on the title bar of any window, the window manager will crash.
Code somewhere in metacity (apparently) frequently scans down the list of workspace names, and uses num_workspaces as a limit for how far to scan. When it increments past the compiz limit of 16, it is referencing uninitialized memory. Results after this are (of course) somewhat unpredictable, but generally the window manager either dies or goes into an infinite loop.
Since the window manager is dead, it is hard to collect data, but I have seen an error message that said something like:
"window manager exception: workspace_name[i] != NULL", I'm really sorry that I didn't write down the exact wording - I'm afraid my recollection isn't good enough to support a pattern search.
I should point out that the compiz limit of 16 workspaces seems to be based on the design of the visual effect added for the workspace switcher -- it goes off the screen if you have a large number of workspaces. However, a large number of workspaces is one of the killer features of the gnome desktop for me (I regularly configure my systems to use 20-30 workspaces, and use them to organize my work), and the limitation in compiz has forced me to turn off visual effects on all my systems. Please Please Please lose the workspace switcher effect, or at least give an option to use the old behavior.
| Kent Crispin (kent-songbird) wrote | #1 |
| Leo Arias (elopio) wrote | #2 |
| affects: | ubuntu → gnome-panel (Ubuntu) |
| Pedro Villavicencio (pedro) wrote | #3 |
| Changed in gnome-panel (Ubuntu): | |
| status: | New → Invalid |
| Kent Crispin (kent-songbird) wrote Re: [Bug 611373] Re: workspace switcher applet crashes window manager | #4 |
I should mention that if you can manage to get gconf-editor going again without a window manager and reset the num_workspaces variable back to 16, magically things will start working again.