In FMP15.0.3 (on MacOS 10.12.4, but also on 10.10.5), I get the following results:
1. Open Script Workspace
2. Click on a comment line: the entire line is selected
3. Press spacebar: the comment line is opened for editing
4. Press enter: the entire line is selected
5. Press the up and down arrow keys to leave and return to the comment line
6. Press spacebar:
FMPA 15 results:
- The comment line is opened for editing
FMPA 16 results:
- The comment line is NOT opened for editing
This is very frustrating when trying to edit my scripts because I prefer to use my keyboard to navigate the script, and the spacebar is a very versatile tool for opening editable components in the SW.
Workaround: type # in the existing comment line to open it.