SUMMARY
It's a good idea to have sticky edges on a multi-monitor setup as provided by Unity. i.e. A user might want to be able to set up a pressure threshold which prevents the mouse from moving between screens inadvertently in certain situations. For example, one might want to have sticky edge during normal usage to keep the cursor on the screen of interest, but not want it while dragging a window between the screens.

STEPS TO REPRODUCE
Move mouse cursor across shared border between two screens on a multi-screen setup.

OBSERVED RESULT
Notice that it is easy to unintentionally move the cursor to the other screen. 

EXPECTED RESULT
A user might want to be able to set up a pressure threshold which prevents the mouse from moving between screens inadvertently in certain situations.

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma:
(available in About System)
KDE Plasma Version: 5.17.5
KDE Frameworks Version: 
Qt Version: 

ADDITIONAL INFORMATION

Perhaps we could have an option in the kscreen UI to configure this.

Other users expressing interest for such a feature:
1. https://askubuntu.com/questions/1056190/when-using-multiple-monitors-in-kubuntu-can-i-make-it-more-difficult-for-the-mo
2. https://askubuntu.com/questions/940496/where-is-the-sticky-edges-option-for-multiple-screens
3. https://www.reddit.com/r/kde/comments/8zbowi/disable_sticky_edges_on_multimonitor/