Menu: should open on mousedown and execute on mouseup

[bpasero]

Refs: #52854

I would expect this to work:

• mouse down
• move the mouse over a menu item
• mouse up

=> action executes

[Tyriar]

👍 was about to create this

[octref]

For me, the expected behavior is execution on mouse up. This is to give people a chance to regret if the misclick on an item - they can move mouse aside and abort the click. This is also how macOS's native dialog works.

[bpasero]

It looks like the behaviour I want is to actually open the menu on mouse down but execute on mouse up, I will update the description.