Fix up process_leader to be a bit more optimized (#4662)

* Fix up process_leader to be a bit more optimized

* Process dual function keys better

* Make leader start a callable function

* Fix per key timer call location

* Add escape if already leading

* Return false for KC_LEAD

* Add documentation

1 files changed, 6 insertions, 0 deletions

diff --git a/docs/feature_leader_key.md b/docs/feature_leader_key.md
index 168a1fc1c..82cf78901 100644
--- a/docs/feature_leader_key.md
+++ b/docs/feature_leader_key.md
@@ -72,6 +72,12 @@ SEQ_THREE_KEYS(KC_C, KC_C, KC_C) {
 }
 ```
 
+## Strict Key Processing
+
+By default, the Leader Key feature will filter the keycode out of [`Mod-Tap`](feature_advanced_keycodes.md#mod-tap) and [`Layer Tap`](feature_advanced_keycodes.md#switching-and-toggling-layers) functions when checking for the Leader sequences. That means if you're using `LT(3, KC_A)`, it will pick this up as `KC_A` for the sequence, rather than `LT(3, KC_A)`, giving a more expected behavior for newer users.
+
+While, this may be fine for most, if you want to specify the whole keycode (eg, `LT(3, KC_A)` from the example above) in the sequence, you can enable this by added `#define LEADER_KEY_STRICT_KEY_PROCESSING` to your `config.h` file.  This well then disable the filtering, and you'll need to specify the whole keycode.
+
 ## Customization 
 
 The Leader Key feature has some additional customization to how the Leader Key feature works.  It has two functions that can be called at certain parts of the process.  Namely `leader_start()` and `leader_end()`.