IBM laptops have this key on top of touchpad that makes point stick to scroll instead of moving the cursor when pressed. How to configure linux to do the same on laptop which doesn't have the physical scroll modifier key. Like for example configuring windows key to do it?
Xorg uses an input driver on linux called
Another approach is via packages
For an example of something vaguely related, and how it was solved with xautomation and xte, see: Where do I start making a linux input hack? on stackoverflow.