I have used the kiosk-application for a keylock, but I can't catch the OK-Button. With the OK-Button, my applications will always be closed. Is there a way to catch the OK-Button or to prevent, that the application always is closing, when the OK-Button is unintentional pressed?
Yes!
If an application is closed, the main form is closed. So you can catch this termination during the sub MainForm_Close Event. The instruction you are looking for is Form.CancelClose.
Is it not possible to hide the task bar at the top of the screen? That way the 'X'/'OK' button at the top right hand corner would not be visible to accidentally click on in the first place.