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TNCS-0029 - OSX Full-Screen Bug When ChronoSync Scheduler Launches

October 23, 2015


When the ChronoSync Scheduler detects an item needs to be run, it launches ChronoSync if it is not already running. When it does this, it explicitly tells the operating system to launch ChronoSync in the background. This is how, under normal conditions, when a scheduled sync comes due, there's no sign that ChronoSync is running other than its icon appearing in the dock. If it was not launched in the background, ChronoSync would appear "on top" of whatever application you were using, a new document would be created and the Scheduled Documents Manager window would appear.

When using ChronoSync in full-screen mode under Lion through El Capitan (macOS 10.7-10.11), the launch of ChronoSync's background scheduler will cause the app to exit out of this mode.

NOTE: This problem has been fixed in Sierra (macOS 10.12).


When running a full screen app/different space under Lion and later, the OS should not alter the state of the full screen app simply because ChronoSync is being launched. It is explicitly being launched in the background. The fact that it affects full screen applications is clearly a bug in the OS. We reported this to Apple quite some time ago and our technical contact at Apple considers it a bug. Unfortunately, the behavior still exists in El Capitan.

We've attempted workarounds with alternate APIs we can use to launch the ChronoSync application. On macOS, there are usually two or three different APIs that can be used to accomplish the same thing, regardless of task. Unfortunately these do not seem to resolve the issue, so this seems to be a bug with the OS and out of ChronoSync's control at this point.


If this is an issue for you, one workaround we suggest is to configure ChronoSync to launch at login and stay running all the time. This 'solves' the problem. You can set this in the 'ChronoSync->Preferences' on the General Pane.

Another workaround is to enable the "Prompt user before running" scheduling option when adding/editing a schedule. In doing this, a notification prompt will be displayed before the sync runs, allowing you to prepare for the eventual loss of full screen. You can either let the prompt sit there until you have finished what you are doing or you can cancel the sync and let it run later when you are not busy.


Feb-20-2017 - Updated to inform fixed in Sierra.
Oct-23-2015 - Created from Internal Support Notes.