Area2D does not report input events if it is not in a collision layer

[alejandrocoria]

Operating system or device, Godot version, GPU Model and driver (if graphics related):
Windows 7 - 64bits
Godot 2.2

Issue description:
Area2D does not report input events if it is not in a collision layer.
I think the collision layers have nothing to do with the detection of input events so it should always detect them (when it is pickable, obviously).

Link to minimal example project:
Area2D Input Bug.zip (Run with Visible Collision Shapes)

[vnen]

Can you reproduce this with Godot 3?

[alejandrocoria]

Yes

[girng]

just ran into this issue good thing i searched before making a new one xD. i checked layer 1 and boom, input detection is working. =]. i had pickable enabled so i was like wtf lol
edit: this happens with KinematicBody2D as well

[lopho]

Can reproduce on 3.1.1.

If this is not fixable due to how mouse picking is implemented, a hint in the documentation and editor would be good to have to avoid confusion.

[KoBeWi]

Likely fixed in #28608
Unless the correct solution would be to somehow change how picking works.

[akien-mga]

I think it can still be considered a bug that picking doesn't work if not in a collision layer. Picking is likely done by a RayCast and thus uses collision layers behind the scene, but in the case of processing input events as a user I wouldn't expect it to matter.

[akien-mga]

Reopening as #40193 was reverted due to #40705.