GNOME Bugzilla – Bug 131378
Alt key modifier conflicts with many window managers
Last modified: 2007-03-07 18:47:42 UTC
From Debian bug report http://bugs.debian.org/227535 (Note: while I don't think this is major, many window managers do make Alt+drag drag the window, and Shift on the erase tool doesn't seem to be doing anything. If Photoshop compatibility is a priority, this might not be an issue at all, but it still should be looked at.) The default window manager for Gnome is sawfish (or is it metacity now?) in both cases alt click is bound to 'move window'. This makes it somewhat difficult to use antierase in the gimp, which is also bound to that key. I can't work out how to change the binding for the gimp (consider this a documentation bug report).
The policy for modifiers is to always provide other ways to achieve the same effect. I don't think Antierase is problematic because you can easily toggle it in the tool options. Same applies for the selection tools that also need Alt but here the problem is worse. But since we came first and it would be very inconvenient to drop this binding, we will probably continue to ask people not to bind Alt to a window manager function.
I suggest marking this bug as a duplicate of bug #120973, or maybe as dependent on it. Note that it raises one new issue: it is not possible for the user to change the bindings for the modifiers. If there is a conflict with the WM usage of the modifiers, those who uses the GIMP frequently can probably accept to change the configuration of their WM, but those who do not use the GIMP that often or cannot change the configuration of their WM for some reason would probably prefer to change the bindings on the GIMP side. Changing the tool code to allow the modifiers to be customized would not be trivial, though. So maybe we should just forget about it and tell the users to customize their environment to suit the GIMP instead of trying to customize the GIMP to suit their environment.
*** Bug 139626 has been marked as a duplicate of this bug. ***
Indeed the problem is not specific to the eraser. As reported in bug #66927 this problem affects also the Alt+Click on the layer mask icon; it also affects several other tools: select, move, scale, crop and path for what I can see. For most of them Alt+Shift+click is a solution, but in the case of the eraser pressing shift makes it collide with the line drawing function.
*** Bug 319179 has been marked as a duplicate of this bug. ***
What should we do with this bug? Many window managers seem to use the special "windows" keys nowadays, so it probably isn't such a big problem anymore to use Alt?
Most don't use the Windows key by default even if they support it, and many keyboards (especially on laptops) don't have extra Windows keys.
I don't think that we will be able to fix this bug. Fortunately, Alt is not used for anything critical and it is usually possible to toggle the corresponding option in the Tool Options tab. As far as I know, the only annoying exception that requires more than one click is for moving selection masks while a selection tool is active: this is only possible with Alt or by switching to the move tool, toggling the "move selection" option and then switching back to the selection tool when it is done. Given that many tools already use the three modifiers (Shift, Ctrl, Alt) alone or in combination, I don't think that we can just sacrifice Alt. Allowing the users to configure the modifiers (as I suggested in comment #2) is not very realistic. I just did a quick grep and I see that the "hardcoded" values GDK_SHIFT_MASK, GDK_CONTROL_MASK and GDK_MOD1_MASK are used in about 380 places in the current code. Regarless of how much this would affect the runtime performance, it would first be a massive task to change the code especially considering the handling of combinations of modifiers like Shift+Ctrl, Shift+Alt and so on. So even though it may not be nice for some users, I will close this as WONTFIX. Users should either configure their WM to use the Windows key or some other key, or they should use workarounds in GIMP such as using the Tool Options instead of pressing Alt.