Using AvalonEdit 5.0.3. There does not appear to be support for regex lookbehind either positive or negative. Lookahead works fine. It appears it chokes on the "less than" character in the lookbehind sytntax.
For instance I have the folloing line where I want to capture the entire line except for the word Note at the begining:
Note Example of IMO 562, severe wind and rolling
Using the following rule:
Results in the following error loading the .xshd file
Name cannot begin with the '=' character