We didn't update the tracks panel y-position in compact mode.
<rdar://problem/30867717>
Created attachment 303510 [details] Patch
Actually, for https://bugs.webkit.org/show_bug.cgi?id=169201, it's more elegant to switch to dynamic positioning of the tracks panel, and this will include the y-position.
*** This bug has been marked as a duplicate of bug 169201 ***