void __touchBegin(EventContext context)
{
if (!_editing || textField.lines.Count == 0)
return;
ClearSelection();
Vector3 v = Stage.inst.touchPosition;
v = this.GlobalToLocal(v);
TextField.CharPosition cp = GetCharPosition(v);
AdjustCaret(cp);
_selectionStart = cp;
context.CaptureTouch();
Stage.inst.onTouchMove.AddCapture(_touchMoveDelegate);
}