Fix auto-selection of URL field with X11 selection
Created by: dmedvinsky
We use focusin event instead of click because when using the latter,
when the selection is created it isn't put into X11 PRIMARY selection.
And as a Linux user I'm very used to such behaviour that when something
gets selected, it's ready for pasting, which is the primary purpose of
the clone URL field.
When focusin is used, the selection is copied to X11 buffer
automatically, so it works as expected (tested in Firefox and Chrome).