Button with two events: onClick AND onRelease? Also getting position of click?

I’m new to Nifti:
How do I write a button that sends an event not only on click, but also on release (in xml)?
Is it possible to get the position of the cursor on a button, maybe for drag? How?
Is there a good tutorial about objects and dragging in Nifti?

Nifty’s Bible.

Read it.