Question

I would like to extended DataGridView to add a second ContextMenu which to select what columns are visible in the gird. The new ContextMenu will be displayed on right click of a column’s header.

I am having difficulty get the correct horizontal position to show the context menu. How can I correct this?

public partial class Form1 : Form
{
    DataGridView dataGrid;
    ContextMenuStrip contextMenuStrip;        

    public Form1()
    {
        InitializeComponent();

        dataGrid = new DataGridView();
        Controls.Add(dataGrid);
        dataGrid.Dock = System.Windows.Forms.DockStyle.Fill;
        dataGrid.ColumnHeaderMouseClick += new System.Windows.Forms.DataGridViewCellMouseEventHandler(ColumnHeaderMouseClick);
        dataGrid.DataSource = new Dictionary<string, string>().ToList();

        contextMenuStrip = new ContextMenuStrip();
        contextMenuStrip.Items.Add("foo");
        contextMenuStrip.Items.Add("bar");
    }

    private void ColumnHeaderMouseClick(object sender, DataGridViewCellMouseEventArgs e)
    {
        if (e.Button == System.Windows.Forms.MouseButtons.Right)
        {
            contextMenuStrip.Show(PointToScreen(e.Location));
        }
    }
}

Answer 1

Where I was going wrong was that DataGridViewCellMouseEventArgs returns the location/x,y of where the mouse clicked within the column header. Instead I need to use HitTest in the grid’s MouseDown event for a hit on the column headers and then convert the position of the hit from the gird co-ordinates to the screen co-ordinates.

public partial class Form1 : Form
{
    DataGridView dataGrid;
    ContextMenuStrip contextMenuStrip;        

    public Form1()
    {
        InitializeComponent();

        dataGrid = new DataGridView();
        Controls.Add(dataGrid);
        dataGrid.Dock = System.Windows.Forms.DockStyle.Fill;
        //dataGrid.ColumnHeaderMouseClick += ColumnHeaderMouseClick;
        dataGrid.MouseDown += MouseDown;
        dataGrid.DataSource = new Dictionary<string, string>().ToList();

        contextMenuStrip = new ContextMenuStrip();
        contextMenuStrip.Items.Add("foo");
        contextMenuStrip.Items.Add("bar");
    }

    private void ColumnHeaderMouseClick(object sender, DataGridViewCellMouseEventArgs e)
    {
        if (e.Button == System.Windows.Forms.MouseButtons.Right)
        {
            contextMenuStrip.Show(PointToScreen(e.Location));
        }
    }

    private void MouseDown(object sender, MouseEventArgs e)
    {
        if (e.Button == System.Windows.Forms.MouseButtons.Right)
        {
            if (dataGrid.HitTest(e.X, e.Y).Type == DataGridViewHitTestType.ColumnHeader)
            {
                contextMenuStrip.Show(dataGrid.PointToScreen(e.Location));
            }
        }
    }
}