Add some magic to the escape key

Behavior:
Normal = Escape
Shift = ~
FN1 = `
FN1+Shift = Shift+Escape

keymap.c

@@ -1,6 +1,9 @@
 #include <stdint.h>
 #include <stdbool.h>
+#include "action.h"
 #include "action_code.h"
+#include "action_layer.h"
+#include "action_util.h"
 #include "bootloader.h"
 #include "command.h"
 #include "keycode.h"
@@ -11,25 +14,45 @@
 const uint8_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
 	// Layer 0
 	KEYMAP(
-		ESC,  1,    2,    3,    4,    5,    6,    7,    8,    9,    0,    MINS, EQL,  BSPC, \
+		FN2,  1,    2,    3,    4,    5,    6,    7,    8,    9,    0,    MINS, EQL,  BSPC, \
 		TAB,  Q,    W,    E,    R,    T,    Y,    U,    I,    O,    P,    LBRC, RBRC, ENT, \
 		LCTL, A,    S,    D,    F,    G,    H,    J,    K,    L,    SCLN, QUOT, BSLS, \
 		LSFT, Z,    X,    C,    V,    B,    N,    M,    COMM, DOT,  SLSH, RSFT, DEL, \
 		FN1,  LGUI, LALT,             SPC,                    FN1,  RGUI, RALT, RCTL),
 
 	// Layer 1: Functions
 	KEYMAP(
-		GRV,  F1,   F2,   F3,   F4,   F5,   F6,   F7,   F8,   F9,   F10,  F11,  F12,  TRNS, \
+		FN2,  F1,   F2,   F3,   F4,   F5,   F6,   F7,   F8,   F9,   F10,  F11,  F12,  TRNS, \
 		CAPS, HOME, UP,   END,  PGUP, INS,  PAUS, TRNS, P7,   P8,   P9,   TRNS, TRNS, TRNS, \
 		TRNS, LEFT, DOWN, RGHT, PGDN, PSCR, TRNS, TRNS, P4,   P5,   P6,   TRNS, TRNS, \
 		TRNS, VOLD, MUTE, VOLU, TRNS, TRNS, TRNS, TRNS, P1,   P2,   P3,   TRNS, TRNS, \
 		TRNS, TRNS, TRNS,             TRNS,                   P0,   TRNS, TRNS, NO)
 };
 
+enum function_id {
+	ESCAPE
+};
+
 const uint16_t PROGMEM fn_actions[] = {
-	[1] = ACTION_LAYER_MOMENTARY(1)
+	[1] = ACTION_LAYER_MOMENTARY(1),
+	[2] = ACTION_FUNCTION(ESCAPE)
 };
 
+void action_function(keyrecord_t *record, uint8_t id, uint8_t opt)
+{
+	if(id == ESCAPE){
+		void (*method)(uint8_t) = (record->event.pressed) ? &add_key : &del_key;
+		uint8_t shifted = get_mods() & (MOD_BIT(KC_LSHIFT) | MOD_BIT(KC_RSHIFT));
+
+		if(layer_state == 0)
+			method(shifted ? KC_GRAVE : KC_ESCAPE);
+		else
+			method(shifted ? KC_ESCAPE : KC_GRAVE);
+
+		send_keyboard_report();
+	}
+}
+
 bool command_extra(uint8_t code)
 {
 	if(code == KC_B){