Fix gnome window screenshot

[jtaala]

This PR fixes #811.

[lost-melody]

Approved, thank you.

One thing I'm confused is that generally for cmp(a, b) we return -1 on (!a && b) and 1 on (a && !b) while here it returns 1 on (!a && b). But I guess it does not matter.

[jtaala]

Approved, thank you.

One thing I'm confused is that generally for cmp(a, b) we return -1 on (!a && b) and 1 on (a && !b) while here it returns 1 on (!a && b). But I guess it does not matter.

It's just a comparator, meaning we're sorting the "windows" that don't have a metaWindow first - it doesn't really matter in this case, but we're aligning to the approach below it:

    if (ia === -1) {
        return -1;
    }
    if (ib === -1) {
        return 1;
    }

which is just ordering the a before b if there no window in that space. It's just for consistency really.

[jtaala]

One thing I'm confused is that generally for cmp(a, b) we return -1 on (!a && b) and 1 on (a && !b) while here it returns 1 on (!a && b)

Ah, apologies, you're right, was looking at the code again - for consistency we should return -1 on !aw. Doesn't essentially matter in this case, but as you pointed out, can be confusing. I'll make that change for consistency and add it to the next PR.