Allow extensions to know if an instance is hidden at start.

GDJS/Runtime/InGameEditor/InGameEditor.tsx

@@ -3347,6 +3347,15 @@ namespace gdjs {
       return !!instanceData && !!instanceData.sealed;
     }
 
+    /**
+     * Instances hidden at start stay visible in the editor, but extensions
+     * can use this to disable what can't be shown as "hidden" (like lights).
+     */
+    isInstanceHiddenAtStart(object: gdjs.RuntimeObject): boolean {
+      const instanceData = this._getInstanceData(object.persistentUuid);
+      return !!instanceData && !!instanceData.hidden;
+    }
+
     private _addInstances(addedInstances: Array<InstanceData>) {
       for (const addedInstance of addedInstances) {
         this._editedInstanceDataList.push(addedInstance);
@@ -3804,6 +3813,7 @@ namespace gdjs {
               );
             }
             runtimeObject.extraInitializationFromInitialInstance(instance);
+            gdjs.RuntimeObject.applyInGameEditorMinimumOpacity(runtimeObject);
           }
         });
       this._updateInstances(instances);

GDJS/Runtime/RuntimeInstanceContainer.ts

@@ -396,6 +396,9 @@ namespace gdjs {
             .getVariables()
             .initFrom(instanceData.initialVariables, true);
           newObject.extraInitializationFromInitialInstance(instanceData);
+          if (this.getGame().isInGameEdition()) {
+            gdjs.RuntimeObject.applyInGameEditorMinimumOpacity(newObject);
+          }
         }
       }
     }

GDJS/Runtime/debugger-client/hot-reloader.ts

@@ -1990,6 +1990,9 @@ namespace gdjs {
       );
       if (numberPropertiesChanged || stringPropertiesChanged || sizeChanged) {
         runtimeObject.extraInitializationFromInitialInstance(newInstance);
+        if (this._runtimeGame.isInGameEdition()) {
+          gdjs.RuntimeObject.applyInGameEditorMinimumOpacity(runtimeObject);
+        }
         somethingChanged = true;
       }
       if (somethingChanged) {

GDJS/Runtime/runtimeobject.ts

@@ -453,6 +453,22 @@ namespace gdjs {
 
     static supportsReinitialization = false;
 
+    /**
+     * Like in the 2D editor, transparent instances stay partially visible in
+     * the in-game editor so they can't be lost or misplaced.
+     */
+    static applyInGameEditorMinimumOpacity(object: gdjs.RuntimeObject): void {
+      const objectWithOpacity = object as gdjs.RuntimeObject &
+        Partial<gdjs.OpacityHandler>;
+      if (!objectWithOpacity.getOpacity || !objectWithOpacity.setOpacity) {
+        return;
+      }
+      const minimumOpacity = 255 / 2;
+      if (objectWithOpacity.getOpacity() < minimumOpacity) {
+        objectWithOpacity.setOpacity(minimumOpacity);
+      }
+    }
+
     /**
      * Return the time elapsed since the last frame,
      * in milliseconds, for the object.