The ability to have one instance of Sublime open across two monitors.
There is already a menu item File/New Window, or is this not what you have in mind?
I was hoping for another window, but without the extra taskbar item. However, the file>new window will suffice.
EDIT:I can't find the function that allows me to move the tabs between two open windows though
Yeah that's a limitation, it's something I very much want to fix in the future.