Subtitles sync-ing broken (when not using -ass)

[qh.dawan@…]

MPlayer SVN-r32719-4.4.5 (gentoo package 1.0_rc4_p20101219).

The behaviour of the keys z/x has changed since SVN-r29796-4.4.3 (gentoo package 1.0_rc4_p20101114), and the behaviour of g/y is broken.

z/x still removes/adds 0.1s to the subtitle delay, but now, this delay is the additional time we have to wait for the subtitle to be displayed, that is to say if a line comes on screen too late, it can be corrected by reducing the delay with z, while with the previous version, I had to enlarge it with x.
In a way it makes more sense, but the old behaviour was coherent with the old g/y, which removed/added enough time to jump to the previous/next subtitle, as described in the man-page.
Moreover, g/y were not swaped in this version, but simply seem to work randomly: if I press quickly on y, the delay should grow and the subtitles should pass faster than intended, but instead the delay oscillates around 0s (eg 6s / 4s / -2s / 4s / and so on) and the subtitles are displayed accordingly.
This happens even if I do it during a video sequence with no subtitle (and the delay will do, for instance, 26s / 24s / -12s / 24s / ...) ; I couldn't get the secret meaning of this erratic back and forth.
For some reason, if I use the y key before the first subtitle line, the delay will grow as it should, though no subtitle will be displayed.

With the -ass option, the old non-broken and non-inverted behaviours come back.