This select modifies the left Expando's easing function. An Expando can have an easeIn and an easeOut parameter. This sets both.
Some easing functions break when used with width: (negative width? but how?). Be warned.
This is a BorderContainer (the window). Each of the panes is set to one of "left", "right", or "center". The left and right panes are ExpandoPanes (they collapse).
We can add other panes programatically:
What does a FloatingPane look like here?