Specifically, I'm installing Kubuntu 12.04 over 13.04. And in fact I've already done it, and it seems to have at least mostly worked, but I'm wondering whether this one anomaly is likely to be attributable to the downgrade; to wit: I have no window borders|decorations, but only wide, featureless, white---or sometimes black---margins around all my windows. None of the settings in System Settings (the window border and decorations options are in Workspace Appearance) seem to have any effect. Is this likely to be fixable, or should I cut my losses and reinstall (formatting the /home partition and restoring any data with rsync)?