Only respond to modifier-only keybindings on release

[spl237]

This is a possible fix for #1756

I have modified the keybinding code so that a flag is set in the keybinding data structure if the keybinding only involves modifier keys.

If this flag is set for a particular keybinding, then that keybinding is detected on key press and stored, and executed on key release if no other (non-modifier) keybinding has executed in the meantime.

This fixes my immediate problem, that of wanting Win+cursor to activate snap behaviour, and Win on its own to launch the application menu, but I have no idea if this is the best way to do this. It seems to work for me, though!

[Consolatis]

I am also not sure the key state tracking is correct here, if we eat the release event but let the press event through to the focused client that will likely result in the client repeating the key on a timer.

In any case I feel very uncomfortable to have this in 0.7.2, the general approach looks good to me though.

[spl237]

Agree this shouldn't be in 0.7.2 - it's a quick hack I put together this morning, and needs a lot of testing for corner cases etc, but if the general approach is ok, I'm happy to look at improvements.

[spl237]

I am also not sure the key state tracking is correct here, if we eat the release event but let the press event through to the focused client that will likely result in the client repeating the key on a timer.

I'm not sure I completely understand the key state tracking, but in an attempt to deal with this, I have modified the code so that the stored key state is only updated on press and not on release - does this look like a better approach?

Interestingly, it has also meant that a modifier-only keybinding is only executed if the key is released relatively quickly, not if it is held down for more than a second or so, which I think is actually better.

[Flrian]

There is also another, older issue for modifier-only keybinds #351
^ Just remembered that one and thought I'd mention it, so it gets closed if this PR fixes the issue.

[Consolatis]

There is also another, older issue for modifier-only keybinds #351 ^ Just remembered that one and thought I'd mention it, so it gets closed if this PR fixes the issue.

For some reason I can't link that issue to this PR (it doesn't show up in the link issue popup). Well, guess we'll have to manually close it then once this is merged.

[ahesford]

Linked. The issue just had to be pinged to convince GitHub that it was still active.

[johanmalm]

Sorry it's taken a while to get to this one. Just working down the list.

What's the best way of testing it? I tried binding to W but can't get it to work.

    <keybind key="W">
      <action name="Execute" command="rofi -show drun"/>
    </keybind>

[spl237]

Bind to Super_L:

<keybind key="Super_L"> <action name="Execute"> <command>wfpanelctl smenu menu</command> </action> </keybind>

I think W is the key when used as a modifier, and Super_L is the same key as a plain keystroke.

[johanmalm]

Bind to Super_L:

<keybind key="Super_L"> <action name="Execute"> <command>wfpanelctl smenu menu</command> </action> </keybind>

I think W is the key when used as a modifier, and Super_L is the same key as a plain keystroke.

Genius. Will have a play 😄