Screenshot filename chooser breaks on filenames with multiple periods (‘.’) in them

[Nathan Phillip Brink]

When I went to save a screenshot named something like 2013.03.19-description.png, I noticed that a file called 2013.png was created at the time that I saved the screenshot.

Instead of breaking on ., the filename messer-upper should start at the end of the filename and backtrack.

[aeichner]

Please reopen if still relevant with a recent VirtualBox release.