Ok, I just landed code for middle-click closing the tab. I also landed code for CTRL+W that will close the current tab. When you get back down to one tab, hitting CTRL+W will close the window.
When you go into tabbed mode, the menu item under file changes from "Close" to "Close Tab", and a new menu item appears underneath it that says "Close Window". This new menu item is bound to ACCEL+SHIFT+W, so you can use that to close a window even when you have multiple tabs open. Try it out and see if this feels intuitive. Later, Dave ([EMAIL PROTECTED])
