We started creating a WPF touch application in Windows 8 and recently migrated to Windows 10. One feature we implemented is opening the Windows Keyboard when a TextBox
I open-sourced my project to automate everything concerning TabTip integration in WPF app.
You can get it on nuget, and after that all you need is a simple config in your apps startup logic:
TabTipAutomation.BindTo();
You can bind TabTip automation logic to any UIElement. Virtual Keyboard will open when any such element will get focus, and it will close when element will lose focus. Not only that, but TabTipAutomation will move UIElement (or Window) into view, so that TabTip will not block focused element.
For more info refer to the project site.
To clarify: If you will be using this package TabTip will not be docked, but your UI will be in view, which i guess is what you wanted to achieve.