qt-bugs@ issue : 208185 
Trolltech task ID : 208349
bugs.kde.org number : 159014
applied: no
author: Robert Knight <robertknight@gmail.com>

When tabs are inserted or removed in a QTabBar, QTabBarPrivate::refresh()
is called to update the layout.  If the tabbar widget is hidden, this
just sets a boolean variable (layoutDirty) and returns, so the parent widget's layout
is not notified about the possible geometry change.

Prior to Qt 4.4 this was not a problem because the geometry was recalculated
in QTabBar::sizeHint() if the layoutDirty variable was set.  In Qt 4.4 however the layout
caches size hint information in QWidgetItemV2.  Since the cache information is not invalidated,
the layout may end up using out-of-date size hint information to compute the widget size.

If the QTabBar is empty when QTabBar::sizeHint() is called, it will return a size with a height 
of 0, which will be kept in the cache and so the tab bar will never be shown.  

This patch fixes the problem by calling updateGeometry() whenever the tab bar's layout is refreshed.

Index: src/gui/widgets/qtabbar.cpp
===================================================================
--- src/gui/widgets/qtabbar.cpp	(revision 796858)
+++ src/gui/widgets/qtabbar.cpp	(working copy)
@@ -533,8 +533,8 @@
         layoutTabs();
         makeVisible(currentIndex);
         q->update();
-        q->updateGeometry();
     }
+    q->updateGeometry();
 }
 
 /*!