Filename disambiguation should be triggered across panes

[peterflynn]

1. Open two files named 'main.js,' one in each pane
2. Compare to result

Result: Both working sets just say "main.js"

Expected: Same as if you'd opened them both in the same pane -- the entry says "main.js - parentFolder" to disambiguate it

[JeffryBooher]

NOTE: This is for the working set

[JeffryBooher]

Update title in lieu of label