View arbitrary file on a different branch?

[AlexVPopov]

If I work on file A on branch X, but I need to consult with the contents of file B on branch Y, how can I do that with the plugin?

In the command line, I'd do that with git show Y:path/to/file/B.

It would be very nice to be able to display the contents of file b form branch Y in a tab.

Thank you very much.