create a Tooltip for the header of a GridViewColumnGroup

[Daniela]

Hi!
I'm looking for a solution to create a Tooltip in the header of a GridViewColumnGroup.

I tried it that way:

GridViewColumnGroup columngroup = new GridViewColumnGroup();

               TextBlock header_block = new TextBlock();
               header_block.Text = purpose.LevelCode;
                ToolTipService.SetToolTip(header_block, purpose.DisplayName);

                columngroup.Header = header_block;
                columngroup.Name = purpose.Id.ToString();
                _visibilityTable.ColumnGroups.Add(columngroup);

but it is not possible -> Exception occures

I tried it another way and set the Tooltip directly to the columngroup but this gave a runtime Exception because the columngroup is not an UI Element.

Is there another possibility (that works)?