Hey, I'm doing a WPF Application.

The tree looks like this:

SurfaceWindow --- Startscreen
..........................-------- Page---------- Subpage

I'm trying to call a method from the "Subpage" from the "Code Behind" of the Startscreen(Startscreen.xaml.cs).

The method from the Subpage looks like this:

public void showTheme(ThemeViewModel theme) { ... }

If know that I can call it when I'm on the "Page" or the "SurfaceWindow", because it's in the same "branch" of the tree, and I just do something like this:

        ThemeViewModel theme = (ThemeViewModel)mvm.CurrentItem.ThemeViewModel;
        katalog.katalogblatt.showTheme(theme);

But how do I do it when I'm not on the same branch of the tree and want to call the method?