Stefan: That code is, I think obsolete since if you check out a remote branch/tag you'll get a detached head and that code only works from the "current" branch when the dialog is initialized.

The "New branch" dialog as I see it is pretty useless with many remote branches. It might be better to integrate the "New" option into the "Other.." menu which brings up a tree view, which is easier to browse and has some filtering capability.

Other than that, I also thing the suggestion should only be present for remote branches and tags.