[Closed] edittext: backspace problem

Hi,

I have this problem with my code.

		on __fileBase changed arg do (
			cutValue = arg.count
			if (matchPattern arg pattern:"*_*" == true) do (
				arr = filterString arg "_"
				arg = ""
				for itm in arr do arg += itm
			)
			__fileBase.text = arg
			A = substring __fileName.text 1 offsetFileName
			print A
			B = substring __fileName.text (offsetFileName + cutValue) 999
			print B
			print cutValue
			__fileName.text = A + arg + B
		)

So the way it works is that each key entered it’s evaluating the code. It is reading itself and than splitting into A (string before) + arg(string entered) + B(string after).

So now when I press backspace it is reading itself but does not cut the string properly. Thats why it fails.

Is there any way I can make a statement that the pressed key is backspace? does mxs can compare keyboard keys?