Merge 909ae884e5 into d79f359c43

ui/src/components/WebRTCVideo.tsx

@@ -332,19 +332,25 @@ export default function WebRTCVideo() {
           // Example: If altKey is true, keep all modifiers
           // If altKey is false, filter out 0x04 (AltLeft)
           //
-          // But intentionally do not filter out 0x40 (AltRight) to enable Alt Gr
-          // (Alt Graph) as a modifier. The altKey attribute is set to false on
-          // key combinations involving the Alt Gr key, which means the modifier
-          // would otherwise be unintentionally removed from the filteredModifiers
-          // list.
-          //
-          // For example, the KeyboardEvent for Alt Gr + 2 has the following structure:
+          // But intentionally do not filter out 0x40 (AltRight) to accomodate
+          // Alt Gr (Alt Graph) as a modifier. Oddly, Alt Gr does not declare
+          // itself to be an altKey. For example, the KeyboardEvent for
+          // Alt Gr + 2 has the following structure:
           // - altKey: false
           // - code:   "Digit2"
-          // - type:   ["keydown"|"keyup"]
+          // - type:   [ "keydown" | "keyup" ]
           //
-          // Adding and removing 0x40 (AltRight) from and to the list of active
-          // modifiers is handled by keyUpHandler an keyDownHandler.
+          // For context, filteredModifiers aims to keep track which modifiers
+          // are being pressed on the physical keyboard at any point in time.
+          // There is logic in the keyUpHandler and keyDownHandler to add and
+          // remove 0x40 (AltRight) from the list of new modifiers.
+          //
+          // But relying on the two handlers alone to track the state of the
+          // modifier bears the risk that the key up event for Alt Gr could
+          // get lost while the browser window is temporarily out of focus,
+          // which means the Alt Gr key state would then be "stuck". At this
+          // point, we would need to rely on the user to press Alt Gr again
+          // to properly release the state of that modifier.
           .filter(
             modifier =>
               altKey ||