Handle messages from on main thread
Handle messages from on main thread

Apparently the pipe listener is on a different thread, so doing UI
actions in response can cause problems.

google/xi-editor,google/xi-editor,google/xi-editor,fuchsia-mirror/third_party-xi-editor,fuchsia-mirror/third_party-xi-editor,modelorganism/xi-editor,google/xi-editor,fuchsia-mirror/third_party-xi-editor,fuchsia-mirror/third_party-xi-editor,modelorganism/xi-editor,modelorganism/xi-editor