I have built BOINC 7.8.6 for the Mac and uploaded it to http://boinc.berkeley.edu/dl. This is a release for Macintosh only; there are no changes from 7.8.3, 7.8.4 or 7.8.5 affecting the code for any other platform. It fixes a couple of Mac-only bugs in 7.8.5:
* Reliably installs the BOINC screensaver (unless asked not to do so.)
* Fixes a bug which could prevent determining the correct size of RAM when run on versions of OS X older than OS 10.11.
Please promote it to recommended version when appropriate.
This allows older project graphics apps to be displayed by the Mac screensaver under OS 10.13 High Sierra, though at a slower frame rate than project graphics apps which have been relinked with the BOINC graphics libraries version 7.8.3 or later. The slower frame rate can make animations appear less smooth.
There is no change in the way the screensaver displays project graphics apps on versions of Mac OS X prior to OS 10.13, whether or not the graphics apps have been relinked.
For older builds of a graphics app, the screensaver will show the moving BOINC logo with the text "Starting screensaver graphics" for 5 full seconds before displaying the graphics. Updated graphics apps will appear more quickly ("Starting screensaver graphics" will appear for less than 5 seconds.)