From the homepage:
"This version mainly fixes all the bugs I could find in 0.50-pre1, and there were quite a few ! It also puts back the default controls for the win32 version (3 for coin1 and 1 for P1 Start), and it adds some options for the game selection dialog.
Sorry no dialog to change the controls yet, you'll have to wait for the next update (that's why it's still a pre-release : some big features are still missing !). It might be the most stable raine version ever though since it fixes very old bugs that I never wanted to fix until now..."