I'm using standard keyboard ( on NB ) to play the game.
I used to use key 5 or 6 to "insert coin" in MAME and key 1 or 2 to start the games in 5.22. However, this doesn't work anymore in 5.23. But the Joystick still works fine.
(I just found that I can use right SHIFT key to insert coin and ENTER key to start 1st player. But how to start 2nd player? Is the key mapping changed?)
Also, the mouse pointer can't be shown in 3DS (citra) emulator in 5.23. (It's ok in 5.22.)
(BTW, mouse is working fine in F1 > FILES)