cubase9 black border underneaht workspace

Hi,

There is a large black border underneath my workspace in cubase,
which I can’t remove.
Is there an option to enlarge the workspace again?

Can someone help me?

thanks!
joes
Screen Shot 2017-03-14 at 11.01.07.png
Screen Shot 2017-03-14 at 10.58.31.png