UI: text-editor.cc: avoid unneccessary async callbacks
UI: text-editor.cc: avoid unneccessary async callbacks

Queing main loop callbacks in excess can fill up the event loop
queues badly, which might take O(n²) complexity to call n callbacks.

Signed-off-by: Tim Janik <6ec6ff229c4e1c5bbd5933ee92e6c5832ff023bb@gnu.org>

tim-janik/rapicorn,tim-janik/rapicorn,tim-janik/rapicorn,tim-janik/rapicorn,tim-janik/rapicorn