Is it possible to show WinForm controls at a PPTX Slideshow by a VSTO Addin?

Question

I want to add and change some WinForm controls during a running slideshow on top of the slideshow window, just by a VSTO Addin. I know there a other possibilities, but our customer is pretty strict. I didn't see any fitting property, but the presentermode got two mouse cursors so its may possible. Thx!

public partial class ThisAddIn
{
    private Control _textbox;
    private void ThisAddIn_Startup(object sender, System.EventArgs e)
    {
        _textbox = new TextBox
        {
            Left = 200,
            Top = 200,
            Multiline = true,
            Height = 120,
        };
        this.Application.Controls.Add(_textbox);
    }
...

Answer 1

There is no trivial way for doing so. However, I believe you can use Windows API functions to set the parent window handle (your presentation view) of the window form.