Thanks John, that works very well!

Just one more question: In presentation mode, the mouse pointer does not appear everywhere on the 2nd trigger field (in your example that would be e.g. a-c trigger / b-c trigger) that I want to click on to start the animation. I think it is because the trigger fields are placed on top of each other, but for some reason in your example it works and in mine it doesn't.
Do you have an idea how I could solve this problem?