Clicking on a file in the File Browser immediately loads a preview of its contents. Works fine for text files, but when the file is binary (eg .image, .png) the above error is raised. Changeset attached in the issue, wrapping on:do: handler around contents-reading calls. The fix as provided is really basic, just to catch the error and display some kind of warning in the file browser itself. Actual proper handling should probably be more refined. http://code.google.com/p/pharo/issues/detail?id=5476