Add tests for buttons.

This way it can be used for testing.

This helps accessibility in general and specifically allows testing for 
it.

#628

...to not be enabled

This is for adding and duplicating sections.

#626

This fixes an issue where items could be added to only-one-item lists 
with replacement, when the  item to be replaced has the same list as 
origin.

#624

Fixed by using styles as in text field to define the background color

#625

#611

#623

#609, #622, #601

#617

#611

#582

#613

#611