Refocus after Dialog close triggers Tab change

The DialogHost tries to "re-focus" the item previously selected. This is the code for it:
https://github.com/MaterialDesignInXAML/MaterialDesignInXamlToolkit/blob/5533b50a6cff78cb75fbb52e16f7c9e06c62446c/MaterialDesignThemes.Wpf/DialogHost.cs#L268

This is very problematic, when the previous control was a TabItem, because Focus()ing a TabItem actually activates the respective tab.

Here is a very simple reproduction:

• Have a TabControl within a DialogHost
• Focus a given TabItem (i.e. by clicking on an already active Tab)
• In the SelectionChanging Event of the TabControl Show the Dialog (i.e. "Loading data ...")
• Click another Tab

The following happens:

• DialogHost remembers, that the first tab is currently focused
• The click on the second Tab activates this Tab
• Dialog is shown and closed again, after data is loaded
• Dialog calls Focus() on first tab
  => First tab will be selected again

I just created the issue as I'm not sure, what the best solution for this. My current feeling tells me to just check for if(!(dialogHost._restoreFocusDialogClose is TabItem), but there might be other elements, where a re-focus is not desired?

I'd be happy to provide a PR after we agree on a solution.

Also - for now, I'd welcome any idea for a good workaround I could place into the application to make it work for now.

Commencez dans DialogHost.cs autour de la ligne 268 et reproduisez l’interaction avec un TabControl, un TabItem et un gestionnaire SelectionChanging qui ouvre une boîte de dialogue. Vérifiez si la restauration du focus sur l’élément précédemment sélectionné doit être ignorée ou traitée différemment pour les éléments d’onglet, et vérifiez que la fermeture de la boîte de dialogue laisse l’onglet nouvellement sélectionné actif.