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Key Toggle Behavior

Summary​

The key toggle behavior toggles the press of a key. If the key is not currently pressed, key toggle will press it, holding it until the key toggle is pressed again or the key is released in some other way. If the key is currently pressed, key toggle will release it.

Example uses for key toggle include shift lock, or ALT-TAB window switching without holding down the ALT modifier.

Behavior Binding​

  • Reference: &kt
  • Parameter: The keycode, e.g. LALT or DOWN_ARROW

Example:

&kt LALT

You can use any keycode that works for &kp as parameter to &kt, however, modified keys such as LA(A) will be toggled based on the status of the base keycode (in this case A). In other words, modifiers are ignored when determining whether or not the key is currently pressed.

Configuration​

Toggle mode​

If you wish to ensure that a key is pressed or released, rather than merely toggling, then you can do so with the toggle-mode property. Define a new behavior and assign "on" or "off" to toggle-mode:

/ {
    behaviors {
        kt_on: key_toggle_on_only {
            compatible = "zmk,behavior-key-toggle";
            #binding-cells = <1>;
            display-name = "Key Toggle On";
            toggle-mode = "on";
        };
    };
};

You can then use &kt_on in place of &kt whenever you wish to only toggle a key on, and not toggle it off. An "off" version of the behavior can be defined similarly.