Xamarin Forms - Edit the Title-Bar

Hi,
I am working in an forms pcl application, where i have a tabbed page. I have hide the title bar.
What i want to ask if there is a way to override(edit) the title bar, thus to add an image, a button and an entry field.
It would be fine if it was possible to add a Stacklayout in the top of the tabs bar but it is. Thats way i am looking to a way for editing the main title bar.

I will really appropriate it if you can help me... or at least you will try .

My code looks like the below:

<TabbedPage.Children>
















</TabbedPage.Children>
</TabbedPage

Thanks,
JJ