What I thought was going to happen
Clicking in the space between options on the "Mipmap Levels" sliders would automatically jump the slider head to the predetermined option (slider snapping).
What actually happened
Clicking on the slider caused the game to hang momentarily (normal behavior), but when the slider was clicked while the game was hanging, the slider head moved to an "invalid" location on the slider (i.e. not one of the options).
How to reproduce
Open the video settings screen
Click (don't drag) the Mipmap Level slider to cause the game to hang momentarily
While the game is hanging, click somewhere on the slider that doesn't correspond to a predefined level (e.g. between 0 and 1). This may not work on the first try, but should happen eventually.
Slider head is in the wrong position
Apparently this also works with Mac's tap-to-click on (sends a mouseDown and a mouseUp event on the same frame).