When drawing an anti-aliased line, a static function gdImageAALine is used instead original gdImageLine. But gdImageAALine's line is always a (perceptually) 1-pixel thick line, regardless of what value was called with gdImageSetThickness.
How to reproduce: Set thickness to n > 1. Draw a line with the antialased color.
Actual results: A 1-pixel wide AA line is drawn.
Expected results: An n-pixel wide AA line is drawn.
Additional info: https://bugzilla.redhat.com/show_bug.cgi?id=198042 (but the patch attached by the bug report above is buggy, I'll attach a fixed one)