Like a lot of things in the tech world these days, it all started with a short question on Reddit:

Keyboard shortcut to search programs in overview like Gnome?
byu/AveryFreeman inkde

Teal;Deer:

I found out the meta-only modifier is one thing that needed to be set in $HOME/.config/kwinrc, but also the ExposeAll=Meta config in $HOME/.config/kglobalshortcutsrc – so there’s two places where it needs to be set. Also, you can add /KWin reconfigure to the end and it should start working immediately (reloads kwin config). But hey, thanks so much for pointing me in the right direction!

(my synoposis in the subred)

The biggest impediment to getting the Gnome-like super key behavior in KDE is getting KDE to interpret a single keypress as a keyboard shortcut. If you look at it critically, you can see there’s a lot going on in that single keypress in Gnome: In Gnome, a single keypress gives you both the open windows overview, and a search bar, and even has additional menus accessible from repeating the action (double-pressing super).

KDE isn’t really able to allow single-keypress shortcuts by default, but there’s a spot they’ve carved out where users can add the behavior if they really want to (I get the sense it’s caveat emptor). I’ve never been particularly interested in sticking to pre-defined conventions, so I set out to find out how we could make super behave like it does in Gnome. It couldn’t be that hard, right?

I wanted to know what was going on under the hood, so I did some digging. The most complete reference on the KDE configuration files I’ve found so far is here: https://userbase.kde.org/KDE_System_Administration/Configuration_Files

There’s a whole bunch of really great examples here: https://userbase.kde.org/Plasma/Tips

There’s some man files that are also helpful here (I don’t think this particular spec has changed from KDE 5 to 6):
https://linuxcommandlibrary.com/man/kreadconfig5
https://linuxcommandlibrary.com/man/kwriteconfig5

I found the shortcuts in KDE6 are located in a file named /home/$USER/.config/kglobalshortcutsrc. They’re grouped by category with the names in brackets, like [ActivityManager], [kmix], etc.

So, related to my question, when I opened this file, under [kwin] I found this:

# $HOME/.config/kglobalshortcutsrc

[kwin]
Activate Window Demanding Attention=Meta+Ctrl+A,Meta+Ctrl+A,Activate Window Demanding Attention
Cycle Overview=Meta+Tab,none,Cycle through Overview and Grid View
Cycle Overview Opposite=none,none,Cycle through Grid View and Overview
. . . 
ExposeAll=Meta,Ctrl+F10\tLaunch (C),Toggle Present Windows (All desktops)
. . .

And when I ran the following:

kreadconfig6 --file kglobalshortcutsrc --group kwin --key ExposeAll

I get this response in my terminal:

. . .  
Meta,Ctrl+F10   Launch (C),Toggle Present Windows (All desktops)

So in reference to the kreadconfig6 syntax, the key is the kwin action named ExposeAll. The group should be the category of actions, [kwin]. The harder part is keeping the description in there when writing from the command line, because it’s tab-separated, \t to the right of the same line. But anyway, I am assuming it would be:

kwriteconfig6 --file kglobalshortcutsrc --group kwin --key ExposeAll Meta"

Or if you needed the descriptor to be in the same line as the value (like in the text file), it would be:

kwriteconfig6 --file kglobalshortcutsrc --group kwin --key ExposeAll Meta\tLaunch (C),Toggle Present Windows (All desktops)"

I’m not sure if kwriteconfig6 can sort out the tab-separated sections on its own, but I imagine it probably can. I have shied away from editing these config files in a text editor just in case there’s some specificity they have regarding tab and whitespace I might mess up, but I imagine it could be one option – if you try it, be sure to use a tabspace v whitespace identifier plugin for vim

Thankfully normal people can add this behavior from the GUI under Ksettings -> Shortcuts -> Kwin, too – so that’s reassuring!

A bigger issue might be specifying that you can use only a modifier key as a shortcut (e.g. meta, alt, shift, etc.) which is what the answer to my reddit question addressed (although I don’t think they were aware, exactly).

Therefore, settings need to be created or modified in two separate places, once for the key behavior, ExposeAll (previous example), and another for allowing the key to behave like a shortcut. As far as I can tell, allowing Meta on its own to ‘be’ a shortcut does need to be invoked at the command line. Here’s the process:

Meta (the keypress) is the key value in the pair, analogous to the example with ExposeAll. It will end up in the config file for kwin:

# $HOME/.config/kwinrc 

[ModifierOnlyShortcuts]
Meta=org.kde.kglobalaccel,/component/kwin,org.kde.kglobalaccel.Component,invokeShortcut,Overview

Coincidentally, there the syntax to add it is provided at the end of the kwriteconfig5 man file I linked above. At the very end, it gives the example:

kwriteconfig5 --file ~/.config/kwinrc --group ModifierOnlyShortcuts --key Meta "org.kde.kglobalaccel,/component/krunner_desktop,org.kde.kglobalaccel.Component,invokeShortcut,_launch"

… which is for launching krunner if you hit meta by itself.

If you’d want the config to be reloaded (to start working immediately) you can add /KWin reconfigure to the end.

So I’m assuming if you already have the ExposeAll behavior in your kglobalshortcutsrc and you run the above argument, it should combine krunner with ExposeAll under the Meta keypress, which is extremely Gnome-like behavior (and pretty exciting!)

TBH I was trying all sorts of stuff when I was doing this and am not sure the exact point at which I got the desired behavior, it might require re-logging in or something like that, too. But these are the two elements you’d need in which to get the Gnome-like action from smashing your Meta key.

One last thing – you may have noticed there’s a more conventional keyboard shortcut Ctrl+F10 for ExposeAll in $HOME/.config/kglobalshortcutsrc – one that actually combines two keys, like normal (gee, seems quaint!)

[kwin]
. . . 
ExposeAll=Meta,Ctrl+F10\tLaunch (C),Toggle Present Windows (All desktops)
. . . 

That’s because the userbase.kde.org site I linked at the top says a single-key shortcut (Meta) might not work if there isn’t a key combination shortcut also configured for the same action (Ctrl+F10)

Lastly, I threw together a little one-liner that dumps all the configs into a single text file for analyzing. It makes them a little easier to sift and not have to open each one individually. Just run it from the $HOME/. folder:

for i in $(ls -a1 .config/k*); do echo "File: $(pwd)/$i"; echo ' '; cat $i; echo ' '; echo '--- end ---';  echo ' '; done > ./kde-config-files.txt

I’ll probably put all my KDE6 configs in a git repo one of these days, but for now, I’m off to study ORM development with Python and SQL… Cheers!