refresh files listing when switching projects

[haraldschilly]

Situation:

1. project A: copy files to project B (which I have opened next to it)
2. switch to project B, which is also showing the "Files" tab.
3. I didn't see the copied files, only after refreshing manually.

Expected: when I switch to a project where the files tab is open, do a refresh of the listing -- similar to the case where I switch from an editor tab to files in the same project …