This seems like an old issue, but still is an annoyance for me:
As described at:
http://railsforum.com/viewtopic.php?id=2228
If you press command-option-down arrow while inside a controller
action which does not have an associated view file in TextMate, you'll
get a dialog asking you to give a name to create a new view file. I
love this feature and I use it a lot, but there is one little
annoyance. When creating the view file, it opens it in a new window,
not the current project window.
Has this been addressed?