Commit b1654af406 moved the panel positioning (and thus that of its
corners) before the panel startup animation. As the panel corners now
are mapped while the panel animation is active, the initial style-changed
signal which triggers another repositioning is received after the
initial layout and the corners end up at wrong positions.
To fix, animate the corner positions as well during the startup
animation - if anyone could actually see the animation, the corners
should animate with the panel anyway ...
https://bugzilla.gnome.org/show_bug.cgi?id=643804
d6e29be980