code: def unmarkCollapsed( self ):
          
          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 )
docs: Unmarks this splitter as being in a collapsed state, clearing any \
          collapsed information.