Deleted the unnecessary cast

up.go

@@ -341,7 +341,7 @@ func (e *Editor) HandleKey(ev *tcell.EventKey) bool {
  // move right until the next primary rune or the end of line
  if e.cursor < len(e.value) {
  e.cursor++
- for e.cursor < len(e.value) && unicode.IsMark(rune(e.value[e.cursor])) {
+ for e.cursor < len(e.value) && unicode.IsMark(e.value[e.cursor]) {
  e.cursor++
  }
  }