[Javascript] 'Permission denied to get property XULElement.selectedIndex' wtf?

[Hakan Magnusson]

I've created a custom event handler for input tags, allowing for 
automatically jumping to the next input field when the maxlength of the 
current one has been filled.

It's working fine, and the only annoyance I got is the following error 
message in the JavaScript console on Mozilla:

Error:
[Exception... "'Permission denied to get property 
XULElement.selectedIndex' when calling method: 
[nsIAutoCompletePopup::selectedIndex]"  nsresult: "0x8057001e 
(NS_ERROR_XPC_JS_THREW_STRING)"

This doesn't break/impact my script or my desired result in any way, 
it's just (very) annoying that Mozilla is doing something with its 
autocomplete-functionality that breaks because of my code. >_<

Anybody know of a way to disable the autocomplete-crap through 
scripting? Or another way around this?

Regards,
H