Hi!
I think it would be nice to be able to place a marker
somewhere in a pattern in the song so that I can later
use a key combo to jump back to this marker or another one.
Maybe something like this already exists and I have missed it?
Nope.
But this type of feature would be the perfect candidate for a Lua tool 
Hehe, Right! I’ll get onto it then 
maybe the script could read out a written down ‘code’ in the draggable comments part between the sequence list & matrix?
Like: ‘(P1,L32)’ in a comment would mean, jump to pattern 1, line 32 if triggering the script keyboard shortcut.
I was thinking more like a bookmarks system.
You’d navigate to the part of the song that you’re interested in - the specific pattern sequencer position and pattern line - and then you’d hit a keyboard shortcut to save that bookmark.
Then there would be other keyboard shortcuts to navigate through the saved bookmarks. Next, previous, first, last, etc. plus maybe some numbered shortcuts to jump to specific bookmarks #1 through #10, etc.
hell yeah, much better!
Both good ideas I think.
It would be great to have apattern URI syntax, like:
rns://song/pattern/[line|dsp|...]/[...]
I think there could be many interesting uses for a URI like syntax for
addressing song content, also for keyboard shortcuts.
Then these could be added to the bookmarks collection.
Hehe, going to do some research 
Edit:
Something URI like is already in the OSC server stuff, maybe that can be used? Not so
familiar with osc…
I can’t find a way to scroll the pattern or place the cursor though, any ideas?