lazy layout update

samples/bin/library/prefabs/layout_prefab.json

@@ -0,0 +1,9 @@
+{
+    "components" : {
+        "named" : {
+            "name" : "layout"
+        },
+        "layout" : {},
+        "layout.dirty" : {}
+    }
+}

samples/bin/library/scenes/sample_09.json

@@ -5,12 +5,7 @@
     },{
         "prototype" : "../prefabs/camera_prefab.json"
     },{
-        "components" : {
-            "named" : {
-                "name" : "layout"
-            },
-            "layout" : {}
-        },
+        "prototype" : "../prefabs/layout_prefab.json",
         "children" : [{
             "components" : {
                 "named" : {

samples/bin/library/scripts/emmy/components/layout.lua

@@ -12,6 +12,9 @@ local layout = {
     ---@type boolean
     disabled = false,
 
+    ---@type boolean
+    dirty = false,
+
     ---@type layout_modes
     mode = layout.modes.horizontal,