[FMX] whats wrong with my if statement?

Everyday i’m slowly getting better at AS! WOO!

But right now i got a problem… i have a button on my timeline that i want to toggle fullscreen mode when the file is played as a projector. On my first frame i have in AS - [AS]fullscreen = 0;[/AS] which i hope sets a variable named fullscreen to a value of 0!

Now the AS in my toggle button is as follows :

on (release) {
if (fullscreen = 0) {
FSCommand("FullScreen", "true");
fullscreen = 1;
} else {
	FSCommand("FullScreen", "false");
}
}

It’s probably blindingly obvious to you whats wrong but could you possibly help out a newb?

Ta!
:beer: