If I make a change to a file in one changelist (e.g. default), then change it in another changelist, the Changes Panel rejects it when I try to commit from there, complaining about a changelist clash. Sometimes it asks whether I want to put it into another changelist, but even if I say 'yes', it still refuses any attempt to commit. It also leaves auto-generated 'error' changelists cluttering up the panel after I have moved files out of them.
When this happens, I've had to commit these files from the editor instead of the Changes Panel.
By all means warn me when a file is changed in more than one changelist and then a commit is attempted, but why stop every attempt to commit the file from the Changes Panel?