If an error pops up in Steam (we saw it in cluster launch), there seems to be no way to dismiss the red screen with the error. Need the ubiquitous "X" in the upper right corner, "OK" button at the bottom, or whatever.
(note, we need to consider more than just "how to make the window go away"; we need a mini-workflow that indicates what the real problem was (e.g., "Cluster Launch failed: Permission denied"))