the outdating GUIs:
everytime ps updates and somethink in the gui changes you dont have to edit one image for each change. You have to edit 3 of them, because there are 3 skins.
Imagine how annoying this must be
Extra skins are cool, it would be even more great if each skin could have its own xmls set. But maybe its just not worh the effort? You do the skin, xmls and then you are doomed for the rest of your life to update them as PS updates, because who else will do it? ;P
The third thing you can try to edit near images and xmls, is the ps source code for each window. With this you are unlimited in what you can do with the gui.
but then you have three things you have to update no matter if it go official or not ;P. Only if it goes official, your job is a bit simpler.
Some stuff what may help you if you are going to play in GUI making:
http://ps-mc.com/forums/viewtopic.php?t=19 <- i try to keep these xmls up-to-date. Read the discussion ;P
paws editor was a bit helpfull but still cumbesome till it didnt stop working for me ;P
PSMapV.exe by LigH is also helpfull in some way
--> here i was hoping to find more links xD <--
Hmmm, maybe It is a good idea to poke Induane to make some entry for GUI making there:
http://vaalnor.mine.nu/psdoc/ ;>