[doktrin]

> The least bad used to be linux with Gnome, which had a bad default configuration but could be quickly configured to work great

I had a pretty unpleasant experience getting multiple monitors to work properly with Gnome. It's been so long I couldn't tell you exactly what the issue was, though.

In contrast, multi-monitors 'just work' on both Windows and OSX, so I wouldn't say they support it "offensively badly".