Apple has released, which brings a pixel-doubled Retina mode to external 4K displays connected to compatible Macs and restores contact and calendar syncing between Macs and iOS devices in iTunes (for full details, read “ ,” 15 May 2014). The Retina mode makes content much sharper, rather than just using all the pixels to create a truly huge desktop.
You can grab the update via Software Update (461 MB) or from (461.7 MB). If you skipped any previous Mavericks updates, you can download a  (947.2 MB) to upgrade directly from any earlier version of 10.9 to 10.9.3.
The 10.9.3 update improves the reliability of a variety of networking activities, including IPsec VPN connections; network home directories; and copying, editing and inspecting file permissions on an SMB file server. Also enhanced is stability when installing configuration profiles and login speed for users in Active Directory groups. In addition, 10.9.3 resolves an issue that prevented installing PostScript Type 1 fonts in Font Book.
On the security front, 10.9.3 includes a number of changes, but nothing new, just the same things that were released last month as part of “” (22 April 2014). Similarly, 10.9.3 includes Safari 7.0.3 in case you hadn’t yet installed it (see “ ,” 3 April 2014).
Previously, it was thought that 10.9.3 might be hiding the
/Users folder, but  revealed that the
/Users/ folder in fact disappears after installing iTunes 11.2 and turning on Find My Mac in the iCloud pane of System Preferences. Bug or feature? Turns out that it was a bug, and Apple released iTunes 11.2.1 to resolve the problem (see “ ,” 19 May 2014).
As always, we recommend holding off on installing 10.9.3 unless you’re experiencing specific problems that it claims to resolve. Let others discover if it causes any unanticipated issues and upgrade in a few days if you don’t see concerning reports online.