Why does it have to be a plain?
This represents what I think you are talking about with a 2D box...
hide mouse : sync on
make object cube 1,10
set camera view 150,0,screen width(),screen height()
do
sync
yrotate object 1,object angle y(1)+0.1
box 0,0,150,screen height(),rgb(0,255,255),rgb(0,0,0),rgb(0,0,0),rgb(255,0,0)
set cursor 0,0
print "Press Space to"
print "enter coordinates"
if spacekey()=1
backdrop off
input "X: ",x#
input "Y: ",y#
input "Z: ",z#
backdrop on
endif
loop
If it really needs to be a plain then look into using
lock object on
Insanity is just a state of mind