it's the same on my samsung omnia.
First, you must set the "menu" of fpsece to a hardware button.
When you click on this button, you'll see the virtual gamepad, maybe correctly, maybe not!
If it's not, like on my omnia, you have to find where to click (by trying many times!!!)......not easy, but that's the only solution to close after playing landscape mode without doing a soft reset.
But in fpsece1.0, it will be fixed, you can easily go back to portrait mode (by clicking in the top right cormer of the screen, just under the fps if they are on), and then quit by clicking the "power off" button for 2 seconds (which avoid to close accidentally)
I'm curious to know how fpsece 0.9.x works on an xperia, could you give the fps on some games?