Since there is no available implementation, you will need to create your own dialog.
See the MahApps.Metro Dialog section at github for further details whether your concern was implemented or not. You may also replace the TextBox
control by a PasswordBox
control in the present code. This shouldn't be a problem since we are talking about just one control which isn't actually quite different than the TextBox
.
UPDATE:
As I was researching for my current project, I found an issue in the MahApps.Metro repository where someone released a login dialog. You might want to check this out. I'm going to use that now.