Doing a single svn merge of a file from a branch to trunk was a disaster. The UI was pretty self explanatory...select the branch to merge from and pick a changeset.
However when I did the merge, I got all kinds of tree conflicts and a bunch of other stuff seemed to go wrong. My changeset didn't even get pulled it. I tried this a few times with same result, coworker had similar problem.
When I did `svn merge -c <revid> branch trunk` on the command line it worked fine. pulled in and merge the single changset.