def unmarkCollapsed( self ):
        """
        Unmarks this splitter as being in a collapsed state, clearing any \
        collapsed information.
        """
        if ( not self.isCollapsed() ):
            return
        
        self._collapsed     = False
        self._storedSizes   = None
        
        if ( self.orientation() == Qt.Vertical ):
            self._collapseBefore.setArrowType( Qt.UpArrow )
            self._collapseAfter.setArrowType(  Qt.DownArrow )
        else:
            self._collapseBefore.setArrowType( Qt.LeftArrow )
            self._collapseAfter.setArrowType(  Qt.RightArrow )