There is a pdf file on using the latest Copy/Paste methods in Drag and Drop mode at:

There are a couple of test builds if anyone using ubuntu 16 or Mint 18 wants to try out early.

https://www.cinelerra-gg.org/download/testing/cinelerra-5.1-20181214-ub16-x86_64-static.txz
https://www.cinelerra-gg.org/download/testing/cinelerra-5.1-ub16-20181211-x86_64-static.txz