Something seems wrong with the layout, JButton showing unexpected behaviour at resize of the window

Question

JRE Version 1.7 Update 3

EXPECTED BEHAVIOUR

As I run the program, it works as expected, everything works smoothly. As when

Answer 1

I am unsure whether I found a solution for your system, but adjusting the code to

colourButton = new JButton( "BALL COLOUR" );
colourButton.setOpaque( true );
colourButton.setBackground( colours[ colourCounter ] );
colourButton.setForeground( Color.WHITE );

works on my system (OS X with Java 1.7). Note the setOpaque call, which is needed so that the setBackground call has any effect as stated in the javadoc of that method:

Sets the background color of this component. The background color is used only if the component is opaque

On OS X, without that setOpaque call your code does not even work before a resize