I don't know how TextMate decides where it's going to put the project drawer (the drawer that slides out when you open a directory or project instead of opening a file), but sometimes the drawer comes out on the left when I want it on the right, and other times it comes out on the right when I want it on the left.
Unfortunately it's not at all obvious how you're supposed to move the project drawer from one side to the other, but after digging through the help documentation I finally found it.
Moving the TextMate project drawer
Assuming that the TextMate project drawer is currently open on the left, and you want it open on the right side, do the following:
- From the menubar select View, then Hide Project Drawer.
- Move your TextMate editor window over to the left side of the screen so the project gutter won't have enough room to open up on that side. (You can move the window all the way to the left if you want, but you don't need to go that far.)
- Select View, then Show Project Drawer, and the drawer will now open on the right side of your TextMate editor.
Hopefully in a future release of TextMate they'll provide a much more intuitive way of moving the project drawer from one side to the other, but that's the way it works right now.