When you get an error in the Dialog editor, it can be a nightmare to debug because you can't see the line numbers that are being referenced. e.g., today I had a simple "expected ; after ) in line 161" error due to a typo that took me ages to find and fix because one of my Dialogs has over 300 lines.
It would be amazing if line numbers could somehow be added to the dialog editor, even if there is the possibility of a small discrepancy between line numbers once the dialog has been converted to regular script. It would still be better than having no reference at all.
So I just found out today that if you double click on an error message, you are taken straight to the line being referenced, even if it's in a dialogue. This kind of makes my request irrelevant, which in a way is great news ;-D
Line numbers were added to 3.6.0 wip, but it's likely we're having another 3.5.1 patch with dialog-related bug fixed, so maybe it may be transferred there too.
Was resolved a while ago, in 3.5.1 P6 to be precise.