The fix will be available in our upcoming Volume 4 SP 1 release which is scheduled to be rolled out at end of January 2019. Would waiting for the official release work for you? Otherwise, we can provide a patch if you can create a direct track support incident.
You can achieve your requirement by using Closing event and add your method when secondary drawer is closing. We have created a sample by using a Closing event. Please have the sample from the following link