Hangul which is language used in Korea is 2byte character. In ordinary editor, one deleting(or movement) is always done only for 1byte character. So for deleting(or movement) of one hangul character two deleting(or movement) has to be done. But if the patch is applied, only one deleting(or movement) is enough.

The patch is not beautiful, but rough one. For the better multibyte feature support, you can refer VIM editor.