Cut and paste out of/ into text fields in a separate window doesn't work

I have a Macintosh Mozilla plugin which puts up a separate window for login information. It seems to work fine, it gets keyboard events like typing and hitting return to hit the default button. HOWEVE开发者_C百科R, it doesn't seem to get cut and paste events. When I hit Cmd-v, the edit menu flashes, but nothing happnes.

Is this a problem with my responder chain? Do I have to specially tell Mozilla that I want these events? or am I likely to have some other problem that I haven't even thought of?

It turns out the problem is that I'm using cocoa windows inside Mozilla, which isn't Cocoa... fail.