this little fella sometimes (pretty often) totally destroy my curves.
what i could memorize so far
handles can be thrown out far away from the actual path. so you have to zoom way out to get that guy back
handles get reversed 180°
Edit – btw: when i don’t write the OS, you can assume that this happens on both my machines: 10.7.5 and 10.9, always with the newest beta of glyphs
undo can be broken, so i have to close the file, restart glyphs and try again
all of this happend on non-crazy, fine-bezier drawings. it might have been that here and there some points did not have handles that are straight horizontal or vertical, due to the design.