How can I make a button on the screen for a interactive function ?
UIQ: Dialog Button for stylus
Do you mean in a dialog box, or picking up a tap on screen?
If you mean a dialog box, have a look at ABOUT on Event Core (www.freepoc.org).
If you mean a tap on screen, Event Core (again!) has code that shows you where a pen taps down and up, so you can use that to realise an area of a screen.