Why

HangableEntityBypass is awesome to label your storage systems. Currently, only paintings and item frames are considered 'hangable entities'. It is very common for players to use signs to label storage systems as well.

Caveats

1. This obviously applies only to signs that are currently attached to a block with an inventory.
2. Signs can be right clicked with dies. This can be replaced by shift-right-click.
3. In some servers, signs can have intricate/command block behavior when clicked. Managing such cases is probably outside the scope of this mod.

This will be a completely separate feature if/when it will be added. It doesn't make sense to put it into the "entity bypass" feature, as signs are not entities, and thus the code needs to be completely different as well.

Btw, there is a mod that does this for signs and item frames, so maybe that could help with developing the tweakeroo feature?
https://github.com/gbl/ClickThrough