After the fixes of bug 721750, the text-shadow property is now correctly applied to selections in Firefox 17.0.1 (Mozilla/5.0 (Windows NT 5.1; rv:17.0) Gecko/20100101 Firefox/17.0). However, as soon as the selection containing object becomes unfocused (i.e. a blue selection turns grey), the text-shadow property no longer applied to the selection. This behavior feels wrong and has probably been missed in the patches (unless I miss some sophisticated CSS magic here). To replicate, open the first testcase, select some text (the shadow disappears). Then click into the address bar to remove the focus (shadow re-appears in the unfocused selection).

Why is this marked "regression"? Before bug 721750 this didn't work at all. Now it works for ::-moz-selection (fixed in bug 721750), but unfocused selections don't actually match ::-moz-selection (see bug 706209), so no ::-moz-selection styles are ever applied to them (you can see the same thing with color, background, etc, not just text-shadow).