Following up on
a suggestion made by markm in another topic, There is a new button, labeled "Mix", to allow the letters of a puzzle to be randomly rearranged, except for the mandatory letter, which remains in the middle. The button is under the recently-introduced backspace button, towards the bottom left of the board:

Also, in 7-by-many puzzles, the Shuffle button now functions as it does in other puzzle types. If any letters have been played, all those letters are shuffled.