Allow applying parameters to all selected notes in piano-roll editor

Currently, if you select a number of notes in a staff (or voice), and then open the piano-roll editor, the notes appear highlighted in yellow as if selected, but Velocity, Pitch, OnTime and Length are grayed out so they cannot be edited. Except perhaps for Pitch (where it may make some sense since at most one would like to transpose all selected notes, instead of colapsing them into a single pitch), it would be nice to be able to apply a given parameter to all notes in a selection. For example, applying a custom Length allows to introduce a special articulation for all notes in the selection.
It doesn't seem to be, currently, a workaround. Each note must be painstakingly changed one by one.