I want to change the text of a Powerpoint shape only during presentation (i.e. while the slide is shown), but not change the text permanently so that it modifies the PPT file.

Currenty I'm subscribing to the event

```
Application.SlideShowNextSlide += OnNextSlide;

```

and then I change the text on one specific shape like this:

```
shape.TextFrame.TextRange.Text = "Hello world";

```

However, when the presentation ends, that text is in the PPT file and Powerpoint asks me whether I want to save the changes.

I want to avoid that my Powerpoint Add-In makes changes to the file.