[UX/UI] Pointer's inconsistencies in the Scenario Editor

[HugoGenillier]

The pointer acts inappropriately when hovering elements :

• The pointer style are sometimes inappropriate or does not update well : when manipulating element inside the scenario box it turns into a hand but when we go outside of the box, it tends to stay a hand. We can see the same type of issue with the double arrows.
• we can have cases like a hand pointer on an element we can't move
• some different styles are applied even when the pointer will do the same action : in the video, both the double arrows and the cross expand the element to the left.
• A hand expands vertically whereas a double arrow or cross expands horizontally

This is disturbing for users who may attempts actions which won't be effective even if the pointer suggests that they will work. The consistency of the different pointer's styles is blurry.

This problem was also noticed by arthur-parmentier in an issue he opened few years ago :
#1005 (comment)

Proposition of improvement :

• Fix the style update issue
• Reduce the number of different styles for the pointer
• Define a unique style for expansion, same for moving objects inside the scenario box

[HugoGenillier]

Some research has been done in this figma mockup.
Note that the cursor's icons aren't from score but should be.