Make an application fullscreen

HI all, I want to make a setting with a fullscreen option. If the fullscreen option is checked, I wanna have my game in a fullscreen mode. But how can I make it?

the variable I use to indicate the fullscreen state is → isFullscreen;

the variable I use to set app setting is static AppSettings appsettings;

another variable I use is static Main app;

So, after the I apply my setting, I write :

if(isFullscreen == 1)





but my application is NOT in fullscreen mode at all…Is there a simple way to make the application become fullscreen?

Thanks in advance…

...and see what happens.