This adds some resource-ownership tracking.

Time to start spreading this out, more.

dw/layout.hh

@@ -158,7 +158,8 @@ private:
 
    Platform *platform;
    View *view;
-   Widget *topLevel, *widgetAtPoint;
+   std::unique_ptr< Widget > topLevel;
+   Widget *widgetAtPoint;
    lout::container::typed::Vector<Widget> *queueResizeList;
 
    /* The state, which must be projected into the view. */
@@ -281,8 +282,8 @@ public:
 
    lout::misc::ZoneAllocator *textZone;
 
-   void addWidget (Widget *widget);
-   void setWidget (Widget *widget);
+   void addWidget (std::unique_ptr< Widget > widget);
+   void setWidget (std::unique_ptr< Widget > widget);
 
    void attachView (View *view);
    void detachView (View *view);