Ideas on how to display a modeless message box as a tooltip

Question

I need to display a modeless message box whenever a user hovers over a menu item. I can't use messagebox.show(...) because it is a modal. So what I did was create a seperate windows form and display the form using the hover event on the menu item. I have 2 problems:

1) When the windows form displays the menu loses its visibility.
2) The windows form does not appear next to the menu item like how a tooltip would.

Any ideas on how I could custmize a component's tooltip that will make it look and act like a windows form?

Answer 1

To answer your second problem:

If you set the form.StartPosition property to FormStartPosition.Manual then you can position the form at the cursor (for example):

form.StartPosition = FormStartPosition.Manual;
form.Location = new Point(Cursor.Position.X - 1, Cursor.Position.Y - 1);

This might help with your first problem too.

If you want the form to behave like a tooltip then if you add the following event handler code it might give you want you want:

    private void Form_MouseLeave(object sender, EventArgs e)
    {
        // Only close if cursor actually outside the popup and not over a label
        if (Cursor.Position.X < Location.X || Cursor.Position.Y < Location.Y ||
            Cursor.Position.X > Location.X + Width - 1 || Cursor.Position.Y > Location.Y + Height - 1)
        {
            Close();
        }
    }

This explains the -1 in setting the form position. It ensures that the cursor is actually on the form when it first displays.

Answer 2

Since Form class is just a wrapper around native window, you can use the following snippet to create your own popup form, that looks almost as tooltip window:

public class PopupForm : Form
{
    private const int SWP_NOSIZE = 0x0001;
    private const int SWP_NOMOVE = 0x0002;
    private const int SWP_NOACTIVATE = 0x0010;

    private const int WS_POPUP = unchecked((int)0x80000000);
    private const int WS_BORDER = 0x00800000;

    private const int WS_EX_TOPMOST = 0x00000008;
    private const int WS_EX_NOACTIVATE = 0x08000000;

    private const int CS_DROPSHADOW = 0x00020000;

    private static readonly IntPtr HWND_TOPMOST = (IntPtr)(-1);

    [DllImport("user32.dll")]
    [return: MarshalAs(UnmanagedType.Bool)]
    private static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, uint uFlags);

    public PopupForm()
    {
        InitializeComponent();
        SetStyle(ControlStyles.Selectable, false);
        Visible = false;
    }

    protected virtual void InitializeComponent()
    {
        FormBorderStyle = FormBorderStyle.None;
        StartPosition = FormStartPosition.Manual;
        ShowInTaskbar = false;
        BackColor = SystemColors.Info;

        // ...
    }

    protected override CreateParams CreateParams
    {
        get
        {
            CreateParams cp = base.CreateParams;
            cp.Style |= WS_POPUP;
            cp.Style |= WS_BORDER;
            cp.ExStyle |= WS_EX_TOPMOST | WS_EX_NOACTIVATE;
            //if (Microsoft.OS.IsWinXP && SystemInformation.IsDropShadowEnabled)
            //    cp.ClassStyle |= CS_DROPSHADOW;
            return cp;
        }
    }

    protected override bool ShowWithoutActivation
    {
        get { return true; }
    }

    public new void Show()
    {
        SetWindowPos(Handle, HWND_TOPMOST, 0, 0, 0, 0, SWP_NOACTIVATE | SWP_NOSIZE | SWP_NOMOVE);    
        base.Show();
    }

    public void Show(Point p)
    {
        Location = p;
        Show();
    }
}

Control this form with Show() and Hide() methods from the outside code.