# Mapping Caps Lock to simultaneous Esc and Super (Mod4)
The `CAPS` key can be mapped to an escape key when pressed once, and a super 
(mod4) key when used in combination with other keys. 

Create the file `/usr/share/X11/xkb/symbols/custom_opts` with the following:

    // Make Caps an additional Escape
    hidden partial modifier_keys
    xkb_symbols "super_esc" {
        key <CAPS> { [ Escape ] };
        modifier_map Mod4 { <CAPS> };
    };

Edit `/usr/share/X11/xkb/rules/evdev` and add a new line in the 
`! option        =       symbols ` section:

      custom:super_esc = +custom_opts(super_esc)

Edit `/usr/share/X11/xkb/rules/evdev.lst` and add a new line the `! option`
section:

      custom:super_esc  Make Caps Lock an additional ESC and Mod4

Restart your X session and apply the setting using your DE's keyboard layout
options.

## Updating the keyboard layout option

### Gnome
Open dconf-editor, and navigate to `org.gnome.desktop.input-sources`. Add
`'custom:super_esc'` to the `xkb-options` list. For example, if you have no
other options set, just use `['custom:super_esc']`. If you have other options
set, separate using commas like so: `['compose:ralt', 'custom:super_esc']`.

You can also use the `gsettings` command to do this via commandline.

### XFCE
Edit `/etc/default/keyboard` and add `custom:super_esc` to the `XKBOPTIONS`
variable (comma-separated).

## Other options
Most laptops have the alt key really close to the windows key, which can result
in accidental keypresses. I like to use the `altwin:alt_win` xkb option (_Alt is 
mapped to Win and the usual Alt_) to make both keys work as alt.