Why is elite opening in client window?

[Paul PG]

New to this title, Elite is opening in a small window called client, cant make it full screen for some reason, I've deleted and tried a fresh install too.

Any idea what I've done wrong here?

 

[Factabulous]

 

[GroG79]

alt-enter (or ctrl-enter) works too

 

[GraphiteGB]

Its so people on their Huge monitor can put the game windowed in a small area and then have web site Inara or EDDB open in another area and Still read the web sites... As well as a media player or audio book player as well..
Alt tab to change to another full window got boring, so you can have a window so you can still access/see other stuff...
If you have tablet or more monitors then you choose the other modes... and have all the rest on other screens...