my setup consists of a G5 DualCore2,3GHz, QT7.11,OSX4.6,
Just try the jit.gl.slab help file.
1) Start qmetro
2) Start metro
As soon as you start the metro the following message is sent for each bang to the MAX window,
error: jit.gl.texture: error binding readback mechanism for capture!
error: jit.gl.pbuffer: error binding invalid pbuffer!
Does not happen on a MacBook (no second screen attached).