Select all text and press -/.

[acgc99]

Select all text and press -/. used to crash app/game. This didn't happen with the rest of keys. The solution created a limitation.

This is a limitation, it will delete all text because _on_text_changed is called twice.

if new_text == "-" or new_text == ".":
	text = ""
	old_text = ""
	old_text_length = 0
#	old_text = new_text
#	old_text_length = 1

The commented lines (and removing the two above) would solve the problem since in the first call -/. is new_text and in the second it would be old_text. But this would break that when deleting 0 from -0/0. also delete -/. and similars.