Proposal 2: Collapsable code events:
Code events take up quite some space in the event sheet. Game Maker handles this issue quite nicely:
If the first line in the code event is a comment then it only displays the comment instead of the code.
Since GD5 is a web page you could also add functionality to show the first few lines of code when you hover the mouse over the code event (in a hovering div) and only show the code editor when you click on the code event.
By the way:
I started using JS in my Sakawochi game for the first time and it totally rocks. You should mention this functionality under features on the homepage. This might attract some more advanced game developers. If you create compex logic / math calculations with lots of temporary variables just with event blocks the event sheet gets quite convoluted. Code events solve this issue perfectly.