CheckBox button and ContextMenuStrip for dropdown menu

Question

I'm tring to implement a button which have a dropdown menu when checked and this menu is gone when unchecked. My problem is I cannot uncheck the checkbox when it or its menu lost focus.

The checkbox's appearance mode is button.

My code:

private void cbSettings_CheckedChanged(object sender, EventArgs e)
{
    if (cbSettings.Checked) {cmsSettings.Show(cbSettings, 0, cbSettings.Height);}
    else {cmsSettings.Hide();}
}

I've tried to uncheck the checkBox on contextMenuStrip's VisibleChanged / Closed event but this caused menu not to hide (or hide and show immediately).

Answer 1

The example below does not, of course, include the code you would need for swapping BackGroundImage of the CheckBox to indicate CheckState. The events to "wire-up" should be obvious. Hope this is helpful.

// tested in VS 2010 Pro, .NET 4.0 FrameWork Client Profile
// uses:
// CheckBox named 'checkBox1
// ContextMenuStrip named 'contextMenuStrip1
// TextBox named 'cMenuSelectionInfo for run-time checking of results

    // used to position the ContextMenuStrip    
    private Point cPoint;

    // context click ? dubious assumption that 'right' = context click
    private bool cmOpenedRight;

    // the clicked ToolStripMenuItem
    private ToolStripMenuItem tsMIClicked;

    private void checkBox1_MouseDown(object sender, MouseEventArgs e)
    {
        cmOpenedRight = e.Button == MouseButtons.Right;
    }

    private void checkBox1_CheckedChanged(object sender, EventArgs e)
    {
        // positioning the CheckBox like this
        // is something in a 'real-world' example
        // you'd want to do in the Form.Load event !
        // unless, of course, you'd made the CheckBox movable
        if(checkBox1.Checked)
        {
            contextMenuStrip1.Show();
            cPoint = PointToScreen(new Point(checkBox1.Left, checkBox1.Top + checkBox1.Height));
            contextMenuStrip1.Location = cPoint;
        }
        else
        {
            contextMenuStrip1.Hide();
        }
    }

    private void contextMenuStrip1_ItemClicked(object sender, ToolStripItemClickedEventArgs e)
    {
        // assume you do not have to check for null here ?
        tsMIClicked = e.ClickedItem as ToolStripMenuItem;

        tbCbMenuSelectionInfo.Text = tsMIClicked + " : " + ! (tsMIClicked.Checked);
    }

    private void contextMenuStrip1_Closing(object sender, ToolStripDropDownClosingEventArgs e)
    {
        e.Cancel = checkBox1.Checked;
    }

    private void contextMenuStrip1_Closed(object sender, ToolStripDropDownClosedEventArgs e)
    {
        if (cmOpenedRight)
        {
            tbCbMenuSelectionInfo.Text += " : closed because : " + e.CloseReason.ToString();
        }
    }

Answer 2

I think your approach of unchecking the check box on the context menu's closed event is a good one, what you need is a bit of "event cancelling logic"(c), like this:

private void OnContextClosing(object sender, EventArgs e)
{
    _cancel = true;
    cbSettings.Checked = false;
    _cancel = false;
}

private void cbSettings_CheckedChanged(object sender, EventArgs e)
{
    if(_cancel)
       return;

    if (cbSettings.Checked) {cmsSettings.Show(cbSettings, 0, cbSettings.Height);}
    else {cmsSettings.Hide();}
}

This will keep your CheckChanged event from re-checking your checkbox.