musescore/MuseScore — pull request #213 by Isenbarth (2013-02-11 11:38:23+00:00)
Title: Add update accidental mode

Adds a new mode of update accidentals. Adding or altering an acidental on any note is valid only to this one note. The new functionality is: When adding or altering an accidental to any note while pressing the ALT key, the change will be valid for the whole measure resp. until the next accident is found.