Touchkit 4 Windows Phone Support: Focus Textfield and Textarea

I´ve tested yesterday the Windows Phone Support of TouchKit 4 and run into the Problem that when i added more Components to a VerticalLayout or VerticalComponentGroup than can be displayed on one page -i. e. the user have to use the Scrollbar- Textfields and Textares can´t be focused on WP any more. The keyboard doesn´t open. I tried it on iOS and this Problem haven´t occur. Is this Problem known? I haven´t find a solution yet.