fix(remote-desktop): release held keys on focus loss (#1498)

plugins/remote-desktop/src/frontend/GuacamoleDisplay.tsx

@@ -345,9 +345,9 @@ export const GuacamoleDisplay = forwardRef<
       (hasKeyboardFocusRef.current || displayIsFocused);
 
     if (!shouldCaptureInput) {
+      keyboard.reset();
       keyboard.onkeydown = null;
       keyboard.onkeyup = null;
-      keyboard.reset();
       return;
     }
 
@@ -366,17 +366,8 @@ export const GuacamoleDisplay = forwardRef<
     };
 
     keyboard.onkeyup = (keysym: number) => {
-      if (!clientRef.current) return;
-      if (!isVisible || !windowFocusedRef.current) return;
-
-      const activeDisplay = displayElementRef.current;
-      const stillFocused =
-        !!activeDisplay &&
-        typeof document !== "undefined" &&
-        document.activeElement === activeDisplay;
-
-      if (!hasKeyboardFocusRef.current && !stillFocused) return;
-      clientRef.current.sendKeyEvent(0, keysym);
+      // Focus loss must still release keys already sent to the remote host.
+      clientRef.current?.sendKeyEvent(0, keysym);
     };
   }, [isVisible]);
 

plugins/remote-desktop/tests/frontend/guacamole-key-release.test.ts

@@ -0,0 +1,105 @@
+import ts from "typescript";
+import Guacamole from "guacamole-common-js";
+import { afterEach, describe, expect, it, vi } from "vitest";
+import displaySource from "../../src/frontend/GuacamoleDisplay.tsx?raw";
+
+// Exercise the display's actual focus callback with Guacamole's real keyboard.
+const source = ts.createSourceFile(
+  "GuacamoleDisplay.tsx",
+  displaySource,
+  ts.ScriptTarget.Latest,
+  true,
+  ts.ScriptKind.TSX,
+);
+let callback: string | undefined;
+function visit(node: ts.Node) {
+  if (
+    ts.isVariableDeclaration(node) &&
+    node.name.getText(source) === "refreshKeyboardHandlers" &&
+    node.initializer &&
+    ts.isCallExpression(node.initializer)
+  ) {
+    callback = node.initializer.arguments[0].getText(source);
+  }
+  ts.forEachChild(node, visit);
+}
+visit(source);
+if (!callback) throw new Error("Missing refreshKeyboardHandlers callback");
+const runRefresh = new Function(
+  "state",
+  ts.transpileModule(
+    `const { keyboardRef, clientRef, displayElementRef, isVisible, windowFocusedRef, hasKeyboardFocusRef } = state;
+    (${callback})();`,
+    { compilerOptions: { target: ts.ScriptTarget.ES2022 } },
+  ).outputText,
+) as (state: Record<string, unknown>) => void;
+
+afterEach(() => {
+  vi.restoreAllMocks();
+  document.body.replaceChildren();
+});
+
+describe("remote keyboard focus loss", () => {
+  it.each(["window", "display", "hidden", "tab"])(
+    "releases held modifiers when losing %s focus",
+    (reason) => {
+      const display = document.createElement("div");
+      display.tabIndex = 0;
+      document.body.append(display);
+      display.focus();
+      vi.spyOn(document, "visibilityState", "get").mockReturnValue("visible");
+      const keyboard = new Guacamole.Keyboard(display) as Guacamole.Keyboard & {
+        press(keysym: number): boolean;
+        release(keysym: number): void;
+        pressed: Record<number, boolean>;
+      };
+      const sendKeyEvent = vi.fn();
+      const state = {
+        keyboardRef: { current: keyboard },
+        clientRef: { current: { sendKeyEvent } },
+        displayElementRef: { current: display },
+        isVisible: true,
+        windowFocusedRef: { current: true },
+        hasKeyboardFocusRef: { current: true },
+      };
+      const refresh = () => runRefresh(state);
+      refresh();
+      const keys = [0xffeb, 0xffe3, 0xffe9]; // Windows, Ctrl, Alt
+      keys.forEach((key) => keyboard.press(key));
+      expect(sendKeyEvent.mock.calls).toEqual(keys.map((key) => [1, key]));
+
+      if (reason === "window") state.windowFocusedRef.current = false;
+      if (reason === "tab") state.isVisible = false;
+      if (reason === "hidden") {
+        vi.spyOn(document, "visibilityState", "get").mockReturnValue("hidden");
+      }
+      if (reason === "display") {
+        state.hasKeyboardFocusRef.current = false;
+        display.blur();
+      }
+      refresh();
+      expect(sendKeyEvent.mock.calls.slice(3)).toEqual(
+        [...keys].sort((a, b) => a - b).map((key) => [0, key]),
+      );
+      expect(Object.keys(keyboard.pressed)).toEqual([]);
+      expect(keyboard.onkeydown).toBeNull();
+      expect(keyboard.onkeyup).toBeNull();
+      keyboard.press(0x6c);
+      keyboard.reset();
+      expect(sendKeyEvent).toHaveBeenCalledTimes(6);
+
+      state.isVisible = true;
+      state.windowFocusedRef.current = true;
+      state.hasKeyboardFocusRef.current = true;
+      vi.spyOn(document, "visibilityState", "get").mockReturnValue("visible");
+      display.focus();
+      refresh();
+      keyboard.press(0x6c);
+      keyboard.release(0x6c);
+      expect(sendKeyEvent.mock.calls.slice(6)).toEqual([
+        [1, 0x6c],
+        [0, 0x6c],
+      ]);
+    },
+  );
+});