일단 setPosition함수를 아래처럼 고치면 동작하긴 하네요 ㅎㅎ

1. setPosition: function(target) {
2. var targetElement;
3. var curleft = curtop = 0;
4. if(target == 'centerOfWindow') {
5. targetElement = document.documentElement;
6. } else if(target == 'centerOfEditor') {
7. targetElement = this.xed.getFrame();
8. var obj = targetElement;
9. while( obj.offsetParent )
10. {
11. curleft += obj.offsetLeft;
12. curtop += obj.offsetTop;
13. obj = obj.offsetParent;
14. } } else if(target == 'nearbyCaret') { throw "Not implemented yet";
15. } else {
16. throw "Invalid argument: " + target;
17. }
18. var targetWidth = targetElement.clientWidth;
19. var targetHeight = targetElement.clientHeight;
20. var dialogWidth = this.form.clientWidth;
21. var dialogHeight = this.form.clientHeight;
22. var x = curleft + parseInt((targetWidth - dialogWidth) / 2);
23. var y = curtop + parseInt((targetHeight - dialogHeight) / 2);
24. this.form.style.left = x + "px";
25. this.form.style.top = y + "px";
26. }
27.