Add optional app specification to user.dock_app_expose.

apps/dock/dock.py

@@ -1,5 +1,6 @@
 from talon import Context, Module, actions, clip, ui
 from pathlib import Path
+from typing import Optional
 
 ctx = Context()
 mod = Module()
@@ -14,17 +15,17 @@ class Actions:
     def dock_send_notification(notification: str):
         """Send a CoreDock notification to the macOS Dock using SPI"""
 
-    def dock_app_expose():
-        """Activate app Exposé using the macOS Dock item for the frontmost app"""
+    def dock_app_expose(app: Optional[ui.App] = None):
+        """Activate macOS app Exposé via its Dock item (for the frontmost app if not specified)"""
 
 
 @ctx.action_class("user")
 class UserActions:
-    def dock_app_expose(app: Optional[App]):
+    def dock_app_expose(app=None):
         if app is None:
             app = ui.active_app()
 
-        app_name = Path(ui.active_app().path).stem
+        app_name = Path(app.path).stem
         dock_items = ui.apps(bundle="com.apple.dock")[0].children.find(
             AXSubrole="AXApplicationDockItem", AXTitle=app_name, max_depth=1
         )