function Button() {
	this.borderColor = "#204a87";
	this.mainColor = "#729fcf";

	this.draw = function() {
		/* somehow draw using the variables above */
	};
}

/* in a completely different file... */

Button.setTheme = function(theme) {
	this.borderColor = theme.buttonBorderColor;
	this.mainColor = theme.buttonMainColor;
}