let's do something a bit more sensible for the default sizeHint(). it's still likely to return 0,0 but it gives us a chance at least at something non-zero

svn path=/trunk/KDE/kdebase/workspace/libs/plasma/; revision=691036

widgets/widget.cpp

@@ -132,7 +132,7 @@ void Widget::invalidate()
 
 QSizeF Widget::sizeHint() const
 {
-    return QSizeF(0.0, 0.0);
+    return size();
 }
 
 QSizeF Widget::size() const