The other message that does gop is coords. I do not know the complete message but this works
[toggle] | [coords 600 600 700 700 1 1 $1( | [s pd-pd-arrayz]
[pd pd-arrayz]
clicking toggle displays or hides [pd pd-arrayz]
I just tried around, and it looks like it does the same as
donecanvasdialog, except the first 2 parameters, x+y canvas size. what you
have as $1 also accept 2, which is the setting for GOP on+"hide object
name and arguments" (quite useful). after that you can add 2 more numbers,
for the x and y margins.
Don't change the settings much while the subpatch is opened, or tcl/tk
will stop responding that well (but it doesn't crash pd).
João