macos: more attempts at correct modifier key handling

Fixes #13880

Author: warmenhoven

input/drivers/cocoa_input.m

@@ -310,6 +310,7 @@ void apple_input_keyboard_event(bool down,
    settings_t *settings         = config_get_ptr();
    bool keyboard_gamepad_enable = settings->bools.input_keyboard_gamepad_enable;
    bool small_keyboard_enable   = settings->bools.input_small_keyboard_enable;
+   unsigned original_code       = code;
 
    if (keyboard_gamepad_enable)
    {
@@ -326,10 +327,15 @@ void apple_input_keyboard_event(bool down,
          character = 0;
    }
 
+   /* Update state for both original and translated keys if different */
+   if (original_code > 0 && original_code < MAX_KEYS)
+      apple_key_state[original_code] = down;
+
    if (code == 0 || code >= MAX_KEYS)
       return;
 
-   apple_key_state[code] = down;
+   if (code != original_code)
+      apple_key_state[code] = down;
 
    input_keyboard_event(down,
          input_keymaps_translate_keysym_to_rk(code),
@@ -441,7 +447,7 @@ static int16_t cocoa_lightgun_aiming_state(
    int16_t res_y               = 0;
    int16_t res_screen_x        = 0;
    int16_t res_screen_y        = 0;
-   
+
    int16_t x = apple->window_pos_x;
    int16_t y = apple->window_pos_y;
 
@@ -679,7 +685,7 @@ static int16_t cocoa_input_state(
                   float axis_threshold           = joypad_info->axis_threshold;
                   const uint32_t joykey          = (bind_joykey != NO_BTN) ? bind_joykey  : autobind_joykey;
                   const uint32_t joyaxis         = (bind_joyaxis != AXIS_NONE) ? bind_joyaxis : autobind_joyaxis;
-                  
+
                   if (binds[port][new_id].valid)
                   {
                      if ((uint16_t)joykey != NO_BTN && joypad->button(joyport, (uint16_t)joykey))

ui/drivers/ui_cocoa.m

@@ -449,13 +449,23 @@ - (void)sendEvent:(NSEvent *)event {
          {
             static NSUInteger old_flags           = 0;
             NSUInteger new_flags                  = event.modifierFlags;
-            bool down                             = (new_flags & old_flags) == old_flags;
+            NSUInteger changed_flags              = new_flags ^ old_flags;
             uint16_t keycode                      = event.keyCode;
+            bool down                             = false;
 
-            old_flags                             = new_flags;
+            /* Determine if the changed modifier is being pressed or released
+             * by checking if it's set in the new flags */
+            if (changed_flags != 0)
+            {
+               /* Find which specific modifier changed and its new state */
+               NSUInteger single_change = changed_flags & -changed_flags; /* Isolate rightmost bit */
+               down = (new_flags & single_change) != 0;
+
+               apple_input_keyboard_event(down, keycode,
+                     0, (uint32_t)new_flags, RETRO_DEVICE_KEYBOARD);
+            }
 
-            apple_input_keyboard_event(down, keycode,
-                  0, (uint32_t)new_flags, RETRO_DEVICE_KEYBOARD);
+            old_flags = new_flags;
          }
          break;
         case NSEventTypeMouseMoved: