C# how to detect if Excel has lost focus

Question

I have an Excel AddIn (written in C# and ExcelDNA) with a form used to allow the user to enter data into a control inheriting from a textbox. The form is modal. Entry into the control causes a contextmenu to appear with choices based upon the user's input.

If the user has entered data and the contextmenu is visible, and the user then makes another application be the active application the contextmenu covers the application.

Is there an event that I can use off of the Excel application to determine that Excel has lost focus?

Answer 1

I figured out a way to make the contextmenu appear and not cover other items. My issue was that the contextmenu was always visible during entry into the textbox because I was setting the AutoClose property to false in the textbox TextChanged event. Now I am setting the AutoClose property to false in the TextChanged event while I re-populate the item list. This is done for any keystroke entered into the textbox after the 3rd character is entered.

I then created a contextmenu Closing event as follows:

    #region Instance Variables
    ContextMenuStrip menuStrip = new System.Windows.Forms.ContextMenuStrip();
    public event EventHandler EntryComplete;
    public event EventHandler EntryNotComplete;
    public event EventHandler EntryError;
    #endregion

    // Control Constructor
    public AutoCompleteTextBox()
    {
        InitializeComponent();

        menuStrip.PreviewKeyDown += menuStrip_PreviewKeyDown;
        this.Leave += AutoCompleteTextBox_Leave;

        // Use closing event so that we can determine when to close the menustrip.
        menuStrip.Closing += new ToolStripDropDownClosingEventHandler(menuStrip_Closing);
    }

    void menuStrip_Closing(object sender, ToolStripDropDownClosingEventArgs e)
    {
        // only close the menu strip when an item is selected or the application loses focus
        if (e.CloseReason != ToolStripDropDownCloseReason.ItemClicked &&
            e.CloseReason != ToolStripDropDownCloseReason.AppFocusChange)
        {
            e.Cancel = true;
        }
    }

    private void AutoCompleteTextBox_TextChanged(object sender, EventArgs e)
    {
        .
        .
        .
        try
        {
            // get information on whether a ToolbarMenuItem has been selected
            MenuItem info = new MenuItem();
            MenuItemInfo selectedToolStripMenuInfo = info.SelectedItem(menuStrip);

            menuStrip.AutoClose = true;
            menuStrip.Visible = false;
            menuStrip.Items.Clear();

            if (selectedToolStripMenuInfo == null)
            {
                EntryNotComplete(sender, e);
            }

            if (base.Text.Length >= 3 && selectedToolStripMenuInfo == null)
            {
                .
                .
                .

                menuStrip.AutoClose = false;

                // foreach loop to add items into list
                foreach (SearchType item in lst)
                {
                    szMenuItem = ...;

                    ToolStripItem tsItem = new ToolStripMenuItem();
                    tsItem.Text = szMenuItem;
                    tsItem.Name = item.DealId;
                    tsItem.Click += tsItem_Click;
                    tsItem.Font = new Font("Courier New", 8.0F, FontStyle.Italic);
                    menuStrip.Items.Add(tsItem);
                }

                Point point = base.Location;
                point.Offset(2, base.Height + 2);
                point = base.GetPositionFromCharIndex(base.SelectionStart);
                point.Offset(2, base.Font.Height + 2);

                base.ContextMenuStrip = menuStrip;
                base.ContextMenuStrip.Show(base.PointToScreen(point));
                base.Focus();

                menuStrip.AutoClose = true;
            }
            else if (base.Text.Length >= 3 && selectedToolStripMenuInfo != null)
            {
                EntryComplete(sender, e);
            }
        }
        catch (Exception ex)
        {
            ErrorDescription = ex.Message;
            menuStrip.AutoClose = true;
            menuStrip.Visible = false;
            EntryError(sender, e);
        }
    }