Another one, although it's not a bug but a "missing feature" (at least in my eyes):
I use these buttons to the left (appearing after declaration of functions) to hide some lines of code. After saving and reopening a script, the hidden lines will be displayed again i.e. the information will not be saved. That's quite annoying as the code is already covering several pages...

EDIT:

I just found another "bug". Sometimes, on a irregular basis, toggling breakpoints will crash the editor. Again I experienced this with my own code and with some of the tutorials.