Difference in creating Application object in WPF and WinForms -

why there difference in way application object created in winforms , wpf?

-> in winforms never created application object. available (i believe singleton pattern). in wpf, although hidden in app.g.cs need instantiate one.

-> in winforms sealed class, in wpf way go inherit it.

is done:

• to able define application in xaml (app.xaml)
• due introduction xbap/navigation projects?

what benefits provide?

i don't know design decision entirely motivated desire able define application object in xaml. that's reason enough, seems me.