Great Skill just found some things that I thought were inconsinent.

You can send a tell/speak in cabal and stay hidden.
You cannot speak in group or leader chat and stay hidden.

You can open/close doors and stay hidden, but eating food or drinking you come out of the shadows. Seems like opening/closing doors would be harder to do in the shadows then eating/drinking. You also cannot get stuff out of your backpack without coming out.

A quick look says that improved hide is checked in all these commands, it just doesn't always work.