Add better click through semantics

include/app/app.h

@@ -10,6 +10,10 @@ enum Type { IMAGE,
             TEXT,
             RECT };
 
+enum ClickMode { PASS,
+                 BLOCK,
+                 IGNORE };
+
 namespace app {
 struct Element {
   Type type;
@@ -19,7 +23,7 @@ struct Element {
   Vec2<float> scale = {1, 1};
   float alpha = 1.0f;
   float z = 0;
-  bool click_through = false;
+  ClickMode click_mode = ClickMode::BLOCK;
   Ruby::Block on_click;
 
   Element(Type type) : type(type) {}
@@ -191,11 +195,12 @@ struct Scene {
       Vec2<float> size = e->size();
       Rect rect = Rect::from(size);
       if (rect.contains(world_to_local(position, e))) {
-        result.push_back(*it);
-        if (e->click_through)
-          continue;
-        else
+        if (e->click_mode == ClickMode::PASS) {
+          result.push_back(*it);
+        } else if (e->click_mode == ClickMode::BLOCK) {
+          result.push_back(*it);
           break;
+        }
       }
     }