With saving and restoring of Layouts per User (works also on StartUp):

With Layout-Presets:

With runtime language changing:

With multiple color designs:

• Caliburn
  https://caliburnmicro.com/
  https://github.com/caliburn-micro/caliburn.micro

• MaterialDesignInXamlToolkit
  https://spiegelp.github.io/MaterialDesignExtensions/
  https://github.com/MaterialDesignInXAML/MaterialDesignInXamlToolkit

• MahApps.Metro
  https://mahapps.com/
  https://github.com/MahApps/MahApps.Metro

• MaterialDesignExtensions
  https://spiegelp.github.io/MaterialDesignExtensions/
  https://github.com/spiegelp/MaterialDesignExtensions

• Savablz
  https://github.com/speedyalibaba/Savablz