Inverse search of a compiled file with
-syntex=1 option is trivial: you just choose
Configure -> Editor -> Kate option from
Okular -> Settings menu, then use
Shift-Click on your favorite line of the pdf file.
What about the forward search? How am I supposed to make Okular show a screen with a particular line pointed to in the Kate editor? Or in an abstract source editor, for that matter. No amount of search shows any clue.
It just works in some LaTeX IDEs, of course, but what is under the hood?