I rewrote @justinedwards.jle's example with an eye for performance; basically avoiding a lot of unnecessary allocations of new Color objects:
findColor = system.gui.color(0, 0, 0)
replaceColor = system.gui.color(255, 255, 255)
def colorFinder(component):
for component in component.getComponents():
if component.background.rgb == findColor.rgb
component.background = replaceColor
if component.foreground.rgb == findColor.rgb
component.foreground = replaceColor
colorFinder(component)
parentWindow = system.gui.getParentWindow(event)
colorFinder(parentWindow)