Implement Manager#handle_pending_events

lib/uh/wm/manager.rb

@@ -14,6 +14,13 @@ module Uh
       def grab_key keysym
         @display.grab_key keysym.to_s, KEY_MODIFIERS[:mod1]
       end
+
+      def handle_pending_events
+        handle @display.next_event while @display.pending?
+      end
+
+      def handle event
+      end
     end
   end
 end