Dominosa: better highlighting UI

[chrisboyle]

sylvester van welij writes:

Clearly the way to solve this puzzle involves checking pairs of numbers. Now in the controls, there is a single column of selectable numbers. One has to press two numbers that will light up in red and green. When one wants another pair, one needs to deselect at least one of the numbers and then select a new one.

It would be better if there were two columns of selectable numbers, one for red, one for green. Each column would act like radio buttons, where pressing one releases the prior one. This way cycling systematically through all numbers would be much more efficient. An extra button to release all selections would be needed.

Not clear how this would work on other platforms (physical keyboard) for users who will not carefully read the manual.