GUAC-870: Always interpret Right Alt as AltGr. This seems the only way to allow proper international typing across all supported platforms. There's no way to detect whether Alt is truly Alt under Mac.

guacamole-common-js/src/main/webapp/modules/Keyboard.js

@@ -328,7 +328,7 @@ Guacamole.Keyboard = function(element) {
         13:  [0xFF0D], // enter
         16:  [0xFFE1, 0xFFE1, 0xFFE2], // shift
         17:  [0xFFE3, 0xFFE3, 0xFFE4], // ctrl
-        18:  [0xFFE9, 0xFFE9, 0xFFEA], // alt
+        18:  [0xFFE9, 0xFFE9, 0xFE03], // alt
         19:  [0xFF13], // pause/break
         20:  [0xFFE5], // caps lock
         27:  [0xFF1B], // escape
@@ -372,7 +372,7 @@ Guacamole.Keyboard = function(element) {
         "Again": [0xFF66],
         "AllCandidates": [0xFF3D],
         "Alphanumeric": [0xFF30],
-        "Alt": [0xFFE9, 0xFFE9, 0xFFEA],
+        "Alt": [0xFFE9, 0xFFE9, 0xFE03],
         "Attn": [0xFD0E],
         "AltGraph": [0xFE03],
         "ArrowDown": [0xFF54],
@@ -776,7 +776,7 @@ Guacamole.Keyboard = function(element) {
         // Release alt if implicitly released
         if (guac_keyboard.modifiers.alt && state.alt === false) {
             release_key(0xFFE9); // Left alt
-            release_key(0xFFEA); // Right alt (or AltGr)
+            release_key(0xFFEA); // Right alt
         }
 
         // Release shift if implicitly released