incompatible with Boss Key? Rated 5 out of 5 stars

Reply to Developer Reply: It is Boss Key's bug
The fact's just like as you said. Yes, you're right. Thanks for your great add-on and fast reply.
I like it much, however Firefox just exit instead of "Close to tray" as Boss Key's setting.

This review is for a previous version of the add-on (0.6.6). 

It is Boss Key's bug

In fact, Boss Key only responds WM_SYSCOMMAND with SC_CLOSE message. If you doesn't install "Hide Caption", press F11 key in Firefox, Firefox will display Minimize, Restore and Close buttons at top-right corner. If you click Close button, firefox exits instead of "Close to tray".

"Hide Caption" has an option "Minimize to the taskbar when user clicks Close button", it is used for "Bos Key" or "Minimize To Tray". In "Boss Key", check "Minimize to tray" ON, and check "Minimize to the taskbar when user clicks Close button" ON, then Firefox will close to tray when you click Close button.