Please note that you should ensure that overflow doesn't happen, not detect when it happens. Once you let it happen, it's undefined behavior.
But you don't need to check each operation to ensure that none of them overflow. If you know that b and c are supposed to be bounded between -10 and +10, for example, the above line can't overflow. So just check that your supposition holds. In most cases, that boils down to a check on the inputs at the entry of the function.
AmigaOS, I believe from 2.0 onwards, could do that[0].
Width and Height being 16bit attributes of the struct for the requested screen.
I haven't seen an actual monitor able to display the whole thing at once, but that's fine, because you can make your screen gigantic yet set the video output to a much lower resolution.
Intuition will let you scroll through it by moving the mouse pointer past the edge.
If inputs come from outside, a vehement Yes!