@Chrisir Yes!!! That works!

And one last question for today…
Since the background color bounces back and forth between 2 random colors, I want to have a completely different random color each time. I added a randomly generated number to the mouseClicked statement (then placed at head of program too as a global variable) but get the same results – only 2 alternating colors.
Again, your thoughts most appreciated!
mouseClicked() now looks like this:
void mouseClicked() {
//int n = int(random(10, 200));
// I want to change background color when I click mouse...
if ( background == color( r1, g1, b1) ) { //!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
background = color(r2/n, g2/n, b2/n);
} else {
background = color(r1, g1, b1);
}
}