Listen events for window management in Manager

lib/uh/wm/manager.rb

@@ -2,6 +2,10 @@ module Uh
   module WM
     class Manager
       INPUT_MASK  = Events::SUBSTRUCTURE_REDIRECT_MASK
+      ROOT_MASK   = Events::PROPERTY_CHANGE_MASK |
+                    Events::SUBSTRUCTURE_REDIRECT_MASK |
+                    Events::SUBSTRUCTURE_NOTIFY_MASK |
+                    Events::STRUCTURE_NOTIFY_MASK
 
       attr_reader :modifier, :display
 
@@ -20,6 +24,7 @@ module Uh
         Display.on_error { |*args| handle_error *args }
         @display.sync false
         @events.emit :connected, args: @display
+        @display.root.mask = ROOT_MASK
       end
 
       def disconnect

spec/uh/wm/manager_spec.rb

@@ -33,6 +33,14 @@ module Uh
           manager.connect
         end
 
+        it 'updates the root window mask in order to manage windows' do
+          manager.connect
+          expect(display.root.mask).to eq Events::PROPERTY_CHANGE_MASK |
+            Events::SUBSTRUCTURE_REDIRECT_MASK |
+            Events::SUBSTRUCTURE_NOTIFY_MASK |
+            Events::STRUCTURE_NOTIFY_MASK
+        end
+
         context 'when connection fails' do
           before { allow(display).to receive(:open) { fail } }