I can't determine when, but often the context menu shows options in gray when they shouldn't because they are activated and you can used them. I have seen this with resize, with paste (after copying files) and with "create new folder" in a mounted partition. The partition was nt protected by permissions and a few seconds later or in another window I could do the operation. Can that be fixed? I don't like that.
This is a bug in 12.04 that's been around for quite awhile & probably will be for some time. (showed up early in Feb. https://bugs.launchpad.net/ubuntu/+source/gtk+3.0/+bug/973491