F5 is shortcut both for Copy button and DirRescan command. Reproducible: Always Steps to Reproduce: 1.emerge gentoo 2.see shortcut for Configuration->Buttons->Definitions->Copy 3.see shortcut for Configure->Controls->Global Keyboard Shortcuts->DirRescan
I installed 0.15.6 and checked, > 2.see shortcut for Configuration->Buttons->Definitions->Copy This is set to nothing. > 3.see shortcut for Configure->Controls->Global Keyboard Shortcuts->DirRescan This is set to F5. So either it's fixed in 0.15.6, or you have some old stray configuration which would imply this as invalid. I'm closing as test-request, please remove all existing old configuration from your home directory and make sure you have done etc-update and try 0.15.6