unselectable Columns and contextmenu problem

[Amine]

Hello
i have some problem about gridvieuw
first :
how to make a columns to Unselectable stat?,i want to prevent the user to clicking on some columns
the second
to solve the first problem I use this method :
the main objectf is to click on specefic cells and capture the value to use in a sql query,so i need to capture the adequate value for the query works.
here is the code :

void GridViewKPI_MouseDown(object sender, MouseButtonEventArgs e)
        {
            RadContextMenu radContextMenu = new RadContextMenu();

            if (GridViewKPI.CurrentCell.Column.UniqueName == "Cell ID")
            {
                TBox_CellID.Text = GridViewKPI.CurrentCell.Value.ToString();

                RadMenuItem copyItem = new RadMenuItem();
                copyItem.Header = "Show In chart";
                radContextMenu.Items.Add(copyItem);
                RadMenuItem pasteItem = new RadMenuItem();
                pasteItem.Header = "Show in Ho Stat";
                radContextMenu.Items.Add(pasteItem);
                RadMenuItem cutItem = new RadMenuItem();
                cutItem.Header = "Show in Map";
                radContextMenu.Items.Add(cutItem);
                RadContextMenu.SetContextMenu(this.GridViewKPI, radContextMenu);

            }
            //else radContextMenu.Items.Remove(copyItem);
        }

The code work fine ,the first time when i click in other cells nothing happens,and when i click in a  specefic cells (Cell ID in my case) the contextmenu appears normally and this is the main objectif,but after this when i reclick in the other cell the contextmenu appears also,and this is my problem,the contextmenu must appears only when i click in a specific columns.
so,how to prevent this to happen?
thanks a lot

[Amine]

Someone can answer me please!