In the older version of Cubase that I use, editor windows cannot undock from the main application window. So I always manually sized the main application window to the max over my desktop that covers 2 monitors. Wondering if there is a utility for that, I realized that the utility AutoHotkey might just do that. After some Googling I found the AutoHotKey script that does the job and here is the zipped stand alone executable.

[Shift] +  + [Up] = Maximize application window on double monitor desktop.
[Shift] +  + [Down] = Maximize application window on main monitor desktop.

+#Up::
    WinGetActiveTitle, Title
    WinRestore, %Title%
   SysGet, X1, 76
   SysGet, Y1, 77
   SysGet, Width, 78
   SysGet, Height, 79
   WinMove, %Title%,, X1, Y1, Width, Height
return

+#Down::
    WinGetActiveTitle, Title
    WinRestore, %Title%
   WinMove, %Title%,, 0, 0, A_ScreenWidth, A_ScreenHeight
return