If I recall correctly, the panel would animation show/hide when set to autohide in KDE4. It doesn't do that in Plasma 5. Is there a reason for this? I like it, provided the animation is quick (like it is when invoking krunner).

autohiding infrastructure saw fundamental changes, leaving several glitches behind.
https://bugs.kde.org/show_bug.cgi?id=354407

Thanks, that was informative. So the animation should appear at *some* time in the future.