Curved bracket version needed for tuplets.
Currently the options for tuplets are to have no bracket at all, or to have the square bracket recommended by modern notation experts.
Both Sibelius and Finale give the option for the bracket to be curved. The fifth edition of Grove's Musical dictionary displays all triplet examples with curved brackets (there's no entry for tuplet), and indeed this was the way I was taught to write them during my formal musical education in the 1960's and early 1970's.
The curved tuplet bracket is also required by scribes producing historically accurate 19th century score.
The forum discussion on this subject can be found here: http://musescore.org/en/node/13199
I propose that the curved bracket be introduced in a future version of MuseScore.