New feature: Change the duration of notes by moving back and forth the next notes of the same measure

Changing a notes' length in MS is not something easy.
Either MuseScore will "eat" the next notes, or it will introduces rest that are difficult to get rid off.
The user is somehow forced to enter its score with the rhythm first, melody second paradigm, while many users would prefer to work with the Melody first, rhythm second paradigm.

This suggestion is about introducing a new way for modifying the rhythm in a measure, allowing the the new Melody first, rhythm second paradigm.

Feature are:
A. Modify a Chord/Rest duration, with impact limited to the measure/track of the selection.
B. Insert a rest before a Chord/Rest, with impact limited to the measure/track of the selection.
C. Time-Delete a Chord/Rest, with impact limited to the measure/track of the selection.

In those 3 use cases, the following rules are proposed :

1. Any action has an impact limited to the track and the measure of the selected chord/rest
2. If the action results in a duration increase, all the following chords/rests must be pushed accordingly further in the measure. This may lead to a measure's duration increase.
3. If the action results in a duration decrease: all the following chords/rests must be pulled accordingly back in the measure. This may lead to a measure's duration decrease.
4. In case of measure's duration decrease, don't decrease beyond the nominative signature, add rests at the end of measure to compensate if necessary.
5. In case of measure's duration decrease, never time-delete anything else than rests on any other staff.

Proof-Of-Concept: