This is just a note to let others know that I am seeing thin "white line" graphic artifacts on the screen after upgrading a Fusion guest from OS X 10.10.2 to the PUBLIC BETA of OS X 10.10.3.
The host is:
21.5 inch mid-2011 iMac 12,1
2.8 Ghz Quad Core i7
16 GB RAM
Mavericks OS X 10.9.5 with the latest updates
The guest is:
Yosemite OS X 10.10.3 BETA
2 processor cores
2048 Mbytes memory
The graphic artifacts appeared immediately after upgrading to 10.10.3 BETA from 10.10.2 release version. They show up when you hover over icons in the dock, when you click on menu items, when you drag windows, etc.
Note: Graphics items have always been slow in Yosemite guests on my system. That is especially true for the username/password login screen and for menus in the menu bar. These thin white line artifacts are new to the 10.10.3 BETA release, however.