This new menu will be opened by hovering over the green “maximize” button in a Mac app window for a split second. The menu will have options for making the window fullscreen, tiling and moving to external displays, including the user’s iPads and external displays connected to the Mac. Selecting one of the display options moves the current window to the selected external display or iPad, in fullscreen.
Presumably the macOS window on the iPad will support touch (the article doesn’t specify). No idea how they’ll handle the smaller tap areas. This seems really cool for DAW plug-ins.