I used to use SwitchTWnd as above but I switched to using "FocusWindow {window name}" and naming the montage window (right click on title bar and set name in config)
SwitchTWnd is documented going to the next trading window and as I wasn't sure where that would always work and whether I would ever use more than one montage I decided to play it safe. I now prefix all of my order commands with an applicable FocusWindow command.