Why jQuery blockUI uses iframe in case of MSIE

Why jQuery blockUI uses iframe in case of MSIE

Hello,

We are facing an issue where we are using jQuery.blockUI plugin and in case of MSIE we get a 404 whenever call to block() is made.

We have narrowed it down to this line of code.

  1. var lyr1 = ($.browser.msie || opts.forceIframe)
  2.         ? $('<iframe class="blockUI" style="z-index:'+ (z++) +';display:none;border:none;margin:0;padding:0;position:absolute;width:100%;height:100%;top:0;left:0" src="'+opts.iframeSrc+'"></iframe>')
  3.         : $('<div class="blockUI" style="display:none"></div>')

It seems what this is saying is if browser is MSIE then use iframe otherwise use div. No other browsers are having issue only in MSIE it seems we are getting an 404 ( GET /K1/themes/sb_top_nav/undefined ) I believe because source of iframe is not being set correctly.

Why in case of MSIE iframe is being used? And why is there a 404, any help will be appreciated.