feat(state): click_at

[EdJoPaTo]

Allows clicking at a given position.

Stores the last area and the y position where items are rendered to determine which identifier was clicked. When it was already selected, toggle it's open/close state.

[EdJoPaTo]

click_at is useful for "don't care, just handle a click". With mqttui also the focus to the given widget is changed which requires knowledge whether something was actually there. So rendered_at is more useful there.

select_at is somewhat of a middle spot. It does the same as click_at except not toggling. But it doesnt allow as much flexibility as rendered_at.

For mqttui I only used click_at and rendered_at: EdJoPaTo/mqttui@3f6f4eb
So maybe remove select_at again? Either do exactly what you want with rendered_at or choose the best effort click_at?

Any thoughts @thscharler ?