When opening a palette (CMD-O, CMD-P), you have to tap the item you want twice. The first time you tap the item in the list, the list will jerk around a bit and then you tap it again and it will open the file or the command you tapped on.
More info, with touch it doesn’t seem to happen, but with the keyboard attached (i have the Apple Magic Keyboard) it does it (clicking on the item using the trackpad)
Here’s a video of it in action. As for the theme, default theme.