Render :back not working with android back button after upgrade to Rhostudio 4.0

[Alps]

Hi

We're having a issue with the android back button since upgrading to version 4.0 of Rhostudio. In version 2.2, the android back button would use the URL set for the render :back => URL. This doesn't work any more on a device since upgrading to version 4.0! The strange thing is it works OK in the Rhosimulator using the the back menu option. 

Has anyone else experience this? Is there another way to detect the android back button click?