In reply to someones post about inventory coloring, it is possible. One of my guildmates did it, didn't take long...Unless I misunderstood the question.
It all has to do with these files...
data>gfx>gui>interface.dds
data>gfx>gui>gui_window_making.dds
data>gfx>image>npcdialogue2.dds
data>gfx>image>gui_reward.dds
I don't know about pets but you can certainly do things such as egos
Here's a better direction to files for you.
Credits to Aokii of course.
Ego replacements/interface/etc. Stuff is still in the making. but those who can draw or want to do their own can use these files and replace them with their own types of addons etc.
Pet is probably a file in the gfx gui. but idk.
And of course you can always scan the files if you don't trust them.
So there oyu go guys, if you feel like changing your inventory colors npc color etc.