diff --git a/lib/cyberarm_engine/ui/container.rb b/lib/cyberarm_engine/ui/container.rb
index bf1f5cd..7854647 100644
--- a/lib/cyberarm_engine/ui/container.rb
+++ b/lib/cyberarm_engine/ui/container.rb
@@ -3,10 +3,11 @@ module CyberarmEngine
     include Common
 
     attr_accessor :stroke_color, :fill_color
-    attr_reader :children
+    attr_reader :children, :gui_state
     attr_reader :scroll_x, :scroll_y
 
     def initialize(options = {}, block = nil)
+      @gui_state = options.delete(:gui_state)
       super
 
       @scroll_x, @scroll_y = 0, 0
diff --git a/lib/cyberarm_engine/ui/element.rb b/lib/cyberarm_engine/ui/element.rb
index 32448f2..4fe7f0f 100644
--- a/lib/cyberarm_engine/ui/element.rb
+++ b/lib/cyberarm_engine/ui/element.rb
@@ -119,17 +119,17 @@ module CyberarmEngine
 
     def toggle
       @visible = !@visible
-      root.recalculate
+      root.gui_state.request_recalculate
     end
 
     def show
       @visible = true
-      root.recalculate
+      root.gui_state.request_recalculate
     end
 
     def hide
       @visible = false
-      root.recalculate
+      root.gui_state.request_recalculate
     end
 
     def draw
diff --git a/lib/cyberarm_engine/ui/gui_state.rb b/lib/cyberarm_engine/ui/gui_state.rb
index 0cacd5f..4bc16ba 100644
--- a/lib/cyberarm_engine/ui/gui_state.rb
+++ b/lib/cyberarm_engine/ui/gui_state.rb
@@ -10,15 +10,18 @@ module CyberarmEngine
 
       @down_keys = {}
 
-      @root_container = Stack.new
+      @root_container = Stack.new(gui_state: self)
       @game_objects << @root_container
       @containers     = [@root_container]
 
+      @active_width  = window.width
+      @active_height = window.height
+
       @focus = nil
       @mouse_over = nil
       @mouse_down_on = {}
       @mouse_down_position = {}
-
+      @pending_recalculate_request = false
 
       setup
     end
@@ -35,6 +38,11 @@ module CyberarmEngine
     end
 
     def update
+      if @pending_recalculate_request
+        @root_container.recalculate
+        @pending_recalculate_request = false
+      end
+
       super
 
       new_mouse_over = @root_container.hit_element?(window.mouse_x, window.mouse_y)
@@ -49,6 +57,11 @@ module CyberarmEngine
       redirect_holding_mouse_button(:left) if @mouse_over && Gosu.button_down?(Gosu::MsLeft)
       redirect_holding_mouse_button(:middle) if @mouse_over && Gosu.button_down?(Gosu::MsMiddle)
       redirect_holding_mouse_button(:right) if @mouse_over && Gosu.button_down?(Gosu::MsRight)
+
+      request_recalculate if @active_width != window.width || @active_height != window.height
+
+      @active_width  = window.width
+      @active_height = window.height
     end
 
     def button_down(id)
@@ -115,5 +128,10 @@ module CyberarmEngine
     def redirect_mouse_wheel(button)
       @mouse_over.publish(:"mouse_wheel_#{button}", window.mouse_x, window.mouse_y) if @mouse_over
     end
+
+    # Schedule a full GUI recalculation on next update
+    def request_recalculate
+      @pending_recalculate_request = true
+    end
   end
 end
\ No newline at end of file
diff --git a/lib/cyberarm_engine/ui/label.rb b/lib/cyberarm_engine/ui/label.rb
index 7777d4a..c713113 100644
--- a/lib/cyberarm_engine/ui/label.rb
+++ b/lib/cyberarm_engine/ui/label.rb
@@ -37,7 +37,7 @@ module CyberarmEngine
       old_width, old_height = width, height
       recalculate
 
-      root.recalculate if old_width != width || old_height != height
+      root.gui_state.request_recalculate if old_width != width || old_height != height
     end
   end
 end
\ No newline at end of file