Thanks for your report, that dialog is part of software-properties, I adjusted the package name. Are there any errors displayed in the file '~/.xsession-errors'? Also, try running 'gksudo software-properties-gtk', does that work for you?
Thanks for your report, that dialog is part of software- properties, I adjusted the package name. Are there any errors displayed in the file '~/.xsession- errors' ? Also, try running 'gksudo software- properties- gtk', does that work for you?