MenuField: enable/disable the menu field when...

the child menu bar or the child menu bar's menu is enabled/disabled.

This means that there is just one status we have to check, the menu
fields, and the child menus agree. This change takes practical form
in the Backgrounds preflet which disables the placement menu when
the image is set to "None", but, only the menu got disabled and not the
parent menu field so the label was erroneously still drawn as enabled.

headers/private/interface/BMCPrivate.h

@@ -52,6 +52,7 @@ public:
 	virtual	void				MessageReceived(BMessage* msg);
 	virtual	void				MakeFocus(bool focused = true);
 	virtual	void				SetMaxContentWidth(float width);
+	virtual	void				SetEnabled(bool enabled);
 
 			void				TogglePopUpMarker(bool show)
 									{ fShowPopUpMarker = show; }

src/kits/interface/BMCPrivate.cpp

@@ -276,6 +276,15 @@ _BMCMenuBar_::SetMaxContentWidth(float width)
 }
 
 
+void
+_BMCMenuBar_::SetEnabled(bool enabled)
+{
+	fMenuField->SetEnabled(enabled);
+
+	BMenuBar::SetEnabled(enabled);
+}
+
+
 BSize
 _BMCMenuBar_::MinSize()
 {

src/kits/interface/Menu.cpp

@@ -1021,6 +1021,9 @@ BMenu::SetEnabled(bool enabled)
 
 	fEnabled = enabled;
 
+	if (dynamic_cast<_BMCMenuBar_*>(Supermenu()) != NULL)
+		Supermenu()->SetEnabled(enabled);
+
 	if (fSuperitem)
 		fSuperitem->SetEnabled(enabled);
 }