Unable to click button in adorner layer

[veronikaaveron]

I have following setup: there is a button "A" that has an adorner containing one other button "B". When I click on that button "A" using

Get<Button>("A").Click();

the adorner with the other button "B" appears for a short time (I suppose the button "A" loses focus after click() somehow, that's why the adorner is gone so fast).

Then I do

Get<Button>("B").Click();

but I get an exception

TestStack.White.AutomationException: Cannot perform action on Button. AutomationId:B, Name:, ControlType:button, FrameworkId:WPF, element is offscreen

Although Get("B").Visible is true.

So my problem is. Button "B" is offscreen obviously because adorner layer of button "A" is not visible anymore. So why does button "A" loose its focus so fast after a click? How can I click on button "B"?