Sorry, sometimes I forget not everyone is on the same boat. Check some of these threads and what they are talking about. It will give you some ideas about how far we have taken the custom skins to protect them from breaking.
http://www.eqgui.com/showthread.php?s=&threadid=3926
http://www.eqgui.com/showthread.php?s=&threadid=3848
And if you do a search for things related to keeping your UI from breaking or patching or the like.
There is a good bit of info there that will explain how some of us have gotten around the problems that Verant imposes everytime they make a change. By doing these things we have made it so that unless Verant make a huge change to the UI system the skin will continue to work without needing to be patched. This last Verant patch was an example. With the new skin that we have out there, there was no need to make any changes to our skins because they came up just fine.