Be able to use the AltGr key to activate a key binding

[idoric]

Unlike the Shift key which causes non-trivial problems, the AltGr key has the sole role of allowing additional characters to be typed. I would like that in the interpretation of key bindings, the AltGr key and the non-modifier key are combined according to the active keyboard layout, before the application of the modifier keys (Super, Ctrl, Alt, and possibly Shift).

Concrete use case: with the French layout Ergo-L, AltGr+r = + and AltGr+t = -, and this is the only way to get these two characters on a 50% (or less) keyboard. It would therefore be very appreciated if Super+AltGr+t were interpreted as Super+(AltGr+t) = Super+- (set-column-width "-10%" by default). It would even be possible to adopt for consistency the Super++ shortcut for set-column-width "+10%", especially since the character r and t (and therefore + and - with AltGr) are side by side on Ergo‑L.

Note that the COSMIC applications don’t do this, but the GNOME and KDE applications do. Firefox also does this, but Discord doesn’t.

[sbroglie]

There is a proposal fixing this (#2134). However, there seems to be no interest by the maintainers to pursuing this. To quote one:

I think what is present right now [in niri] is more or less correct tbf

[idoric]

I find this proposal very interesting, but perhaps it’s too ambitious. Perhaps we should see how to cut it into different parts, to advance by smaller steps.

Anyway, as I indicated at the beginning of my first message, the AltGr key, due to the fact that it doesn’t exist on US Qwerty layout, never appears in key bindings, so there’s no danger in consuming it (to use the vocabulary of the link you indicated to me), and this single change would greatly improve Niri's compatibility with national default configurations (the Wikipedia page of AltGr lists 29 countries concerned, but there are also many alternative layouts, some relatively popular in their respective country or language community).

[flowerysong]

@idoric Unless I'm missing something (which is possible, keyboards are complicated) AltGr is just another name for ISO_Level3_Shift/Mod5, which is supported for use as a modifier in key bindings so it probably is used in some people's keybinds already and there is danger in changing how it's treated.

[idoric]

I have never encountered an application, a game or a desktop environment with shortcuts requiring AltGr, at least in default configuration (I note that GNOME refuses to take AltGr into account when creating a custom shortcut), but whatever, I presume that from the moment Niri allowed this possibility, a few people with a particularly imaginative mind were able to make use of it.

If it’s essential to maintain strict compatibility with existing configuration, the solution could only be a little more complex. One possibility would be to take up my idea about the shift key, but including AltGr: if the key combination doesn’t correspond to anything, consume AltGr if present, if it still does not give anything consume Shift if present.

But in which case, we might as well go all the way to the end of the idea : if the key combination doesn’t correspond to anything, consume all iso_level5_shift if present, if that’s not enough iso_level3_shift, and finally if necessary Shift. (I assumed that Ctrl, Alt and Super are never used to form characters, but at the point where I am at I would only be half surprised if I was proved wrong.)

Note that Shift remains a special case because it’s the only one among the three to appear in the default key bindings, so the second fall back present in my proposal about Shift could be maintained, but only for Shift, and would be added to the end of the test chain.

Thank you for your intervention, I have the feeling that now my proposal is more solid.

[idoric]

@flowerysong I realize that this possibility of using AltGr in a key binding allows me to bypass the fact that AltGr is not consumed before looking for a key binding corresponding to the key combination pressed.

And so, I replaced Mod+Minus { set-column-width "-10%"; } with Mod+ISO_Level3_Shift+T { set-column-width "-10%"; } (because with my keyboard layout AltGr+t = Minus), and it works! (Note that ISO_Level3_Shift was not my first idea, I first tried AltGr, RAlt other variants.)

The fact that I didn't understand this from the moment I read your message shows how counterintuitive it’s to me. But now I realize that this is a very good reason to use AltGr in the definition of a key binding, so I was mistaken in stating that very few people had done it.

However, I don’t think that this solution satisfies all cases. I wonder about people who use two layouts alternately, and the problem of the first connection where MOD+SHIFT+/ (and other key bindings) is inaccessible because / is obtained using AltGr.

However, for me, this is a solution that I can manage with in my specific case, so I could close this thread as resolved, but maybe others will want to continue this exchange of ideas in the future.