Yes, in this case square up inside the coloured frame. I have often 'blocked' a panel when it is bowed or skewed. I take the straightest edge and tape it to my table or floor. Then 'persuade' the rest of the panel to become square with the first edge, usually by dampening, gently stretching (or bunching) the edges, taping down and then wetting thoroughly and letting it dry. I will use it immediately so that it retains the 'corrected' shape.