Idea for the UI… option to autotwist pairs. Such that if you select, say, GC, every time you place a pair, the next pair swaps what is going to be placed. Presently, G always gets placed under the mouse. Adding the easy-to-toggle option would mean G then C then G then C… would speed up initial-filling-in of challenges and many player puzzles.
I didn’t know that the G always got placed under the mouse, that is a cool feature already - I’ve been having to go back and retwist misaligned pairs when I was just 'quickly painting up the line of bases.