File list has border on click

[kulmann]

When you click into the file list, the list has some kind of selection border in blue (see screenshot). Need to bisect when this was introduced. Probably with the permanently visible left sidebar.

Steps to reproduce

1. Open phoenix.owncloud.com
2. Click on anything in the file list (whitespace, row, ...)
3. A blue border around the file list area appears

Expected behaviour

No selection border appears.

Actual behaviour

A selection border appears.

Client configuration

Browser: Chrome for macOS (doesn't happen in Safari)

Operating system: macOS

Screenshot