I have run into issues when hosting a WinForms form within a `WindowsFormsHost` and the tab navigation. To solve I have made this simple example:

* Created WPF `Window` (starting point of app)
* Created WinForms `Form` with two `TextBox` on it
* WPF window: Added `WindowsFormsHost` to it
* WPF window: Added `OnLoaded` handler
* WPF window: Added `Textbox` positioned under the `WindowsFormsHost`

In the `OnLoaded` handler I got:

```
System.Windows.Forms.Form f = new WinFormsForm();
f.TopLevel = false;
f.FormBorderStyle = System.Windows.Forms.FormBorderStyle.None;
this.windowsFormsHost1.Child = f;

```

When I now run the application:

* Nothing is focussed (ok)
* I click on the first `TextBox` in the `WindowsFormsHost`, it gets focus (ok)
* I press tab, focus goes to 2nd `TextBox` in the `WindowsFormsHost` (ok)
* I press tab again, focus goes back to 1st `TextBox` in the `WindowsFormsHost` (**not** ok; should have left `WindowsFormsHost` and given focus to the textbox at the bottom of the WPF window)
* I click on the textbox in the wpf (placed after and under the `WindowsFormsHost`), it gets focus (ok)
* I press tab, focus goes to 1st textbox in `WindowsFormsHost` - as it should go to beginning after the end. So this is ok too
* I click the wpf textbox again and press shift+tab, focus goes to 2nd textbox in `WindowsFormsHost` (ok)
* I press tab, focus goes to 1st textbox in `WindowsFormsHost` (goes to beginning in WFH) (**not** ok)

How do I make the focus behave like if I had only controls of one type? Meaning a tab order of WFH-1st-Textbox, WFH-2nd-Textbox, WPF-Textbox in this case.