To switch between instruments, both columns (description and chart) in the instrument area are clickable, but when you click on any of the charts, the time range selection box is drawn, even tough you haven't clicked and dragged, which is what should start the selection.
Fixed in version 0.33.1.99 (master)
Author: Jose Miguel Torres
Commit: d8fe8650f0d7ce0cd5c1c73f650af4bcbc10a1d7 (xamarin/profiler)
This issue does not exist with latest profiler build i.e. v.0.33.2-0. Here is the screencast for the same: http://www.screencast.com/t/n5oJzpt5AHw