Lock the Playback cursor to mouse when zooming from timeline

Still not fixed in 9.0 (broken since 8.0) 2 years ago.

https://www.steinberg.net/forums/viewtopic.php?f=228&t=70485

2 years and lots of complaints and no reason given - Steinberg seems to have filed this problem in the “zero fucks given” folder.

Way to fix a problem that didn’t exist!