rm one Q_OBJECT macro; protect others against removal by explanatory notes (#521)

This resolves #521 (closed).

GUI/View/SampleDesigner/LayerForm.h

@@ -24,7 +24,7 @@ class WidgetMoverButton;
 
 //! Form for editing a layer
 class LayerForm : public QGroupBox {
-    Q_OBJECT
+    Q_OBJECT // critically important ... even if we don't understand why
 public:
     LayerForm(QWidget* parent, LayerItem* layer, SampleEditorController* ec);