WAIQWatch plugin improvements
WAIQWatch plugin improvements

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

facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper