Prompts the user to pick a new color for the inputed item/column.
        
        :param      item  | <XColorTreeWidgetItem>
                    index | <int>

def editColor( self, item, index ):
        """
        Prompts the user to pick a new color for the inputed item/column.
        
        :param      item  | <XColorTreeWidgetItem>
                    index | <int>
        """
        if ( not index ):
            return
            
        newcolor = QColorDialog.getColor(item.colorAt(index-1), self)
        
        if ( not newcolor.isValid() ):
            return
            
        endIndex = index + 1
        if ( self.propogateRight() ):
            endIndex = self.columnCount()
        
        for i in range(index, endIndex):
            item.setColorAt(i-1, newcolor)