The UI dialog window has z-index:1002 The udf-container has z-index:101

Maybe to calculate z-index should be iterated element.parents() and use as value {max}+1

This can be seen on Firefox 3.5 / Windows.

yes, there was also a code change in SVN, will be with next release. the zindex was not set on the correct item.

Sorry have re-read and understood your request:

option for: iterate ancestors and get z-index; set to max+1. Will have a performance penalty so will optional, off by default.

option to inherit zIndex from ancestors in trunk SVN code. Will be included with next release.

set option: {calculateZIndex: true}