I don't see how to include pictures here, or I would show you. Stay with the long description. This was a feature of a notation program that I had in 1986 on an Atari computer! (yeah, I'm *that* old)
Why not include a special "duple-triple" selector in note entry? Entering music that shifts from regular duple (eighth notes) to triplet (eighth note triplet) should be as easy as shifting from eighth note to quarter note. The current tuplet system is more awkward than it should be.
You would click on the added button to change modes. The appearance of the button will change depending on the mode. When duple (this is how it is now) it would show two eighth notes beamed. When in triple mode it would show three eighth notes beamed. In triple mode, if you select eighth note and enter a note, it would start an eighth-note-triplet to cover one quarter note. In duple mode, the eighth note would be just as it is now. Triplet mode quarter note will start a quarter-note-triplet that covers two beats.
This is not a replacement for the current tuplet system. I only want to enhance note entry. This enhancement would make it easier to enter triplets. Other tuplets would be done with the current setup.