set corona stickyFocus property to true.

This means that clicking on an inactive widget doesn't reset the focus, done for 2 reasons:
* consistence: same behaviour as QWidgets and top level windows
* bugfix: the plasmaboard on screen keyboard now can send input to desktop widgets 


svn path=/trunk/KDE/kdelibs/; revision=1213727

corona.cpp

@@ -86,6 +86,7 @@ public:
 
     void init()
     {
+        q->setStickyFocus(true);
         configSyncTimer.setSingleShot(true);
         QObject::connect(&configSyncTimer, SIGNAL(timeout()), q, SLOT(syncConfig()));