added ui elements with children

src/lib/ui/Canvas.hx

@@ -1,5 +1,6 @@
 package lib.ui;
 
+import util.Rect;
 import util.Vec.Vec2;
 import kernel.ui.Pixel;
 
@@ -55,6 +56,13 @@ abstract Canvas(Array<Array<Pixel>>) to Array<Array<Pixel>> {
 
 		return max;
 	}
+
+	public function getBounds(): Rect {
+		return new Rect({x:0,y:0},{
+			x: maxWidth(),
+			y: hight()
+		});
+	}
 }
 
 class CanvasKeyValueIterator {