Summary:
Improving usability of the WAIQWatch plugin.
Also fixing a bug in `MasterDetail`, which didn't use `sidebarSize` as `height` when detail panel is shown at the bottom.
iOS companion diff here: D28756787
Reviewed By: tomw
Differential Revision: D28751609
fbshipit-source-id: ba27ae7ce3596179752c963dba1bf4b994767c2a