thanks a lot for this topic. I hope it's gonna be very helpful. I am trying to start using devil's pie and cannot make it work.

I tried firefox, but then decided to test something simpler: mousepad text editor.

So I get devilspie running in the terminal and launch mousepad:
Window Title: 'Mousepad'; Application Name: 'mousepad'; Class: 'Mousepad'; Geometry: 1012x667+6+53
So I assume that Application Name is 'mousepad'.

So I created ~/.devilspie directory ad put test.ds file their with the following syntax:
(if (is (application_name) "mousepad") (set_workspace 1))
So I killed devilspie and launch it again to be on the safe side. Now I launch mousepad from workspace 4, assuming that it will appear on the workspace 1, but it is still on 4. What dod I do wrong?