Describe the request
Make sure to include:

1. What problem or issue would this enhancement solve?
   Allows for making TFC leaves solid, like vanilla/other mods, and allows mods like Passable Leaves to change how dense TFC leaves are.

Meta Info

• TFC Version: 1.12.2-29.5.120 (at time of request)
• Is this a compatibility feature for other mods? Or a enhancement for TFC alone?
  Yeah.
• If necessary, what other mods (including versions) would this require?
  Nah.

Why not implement configs for it in TFC?
Does passable leaves do something else TFC doesn't do?

I'd also point out:

• Passable leaves is a core mod (ugly), so you're asking for a config option, to let another mod ASM into vanilla code in hopes of modifying our behavior.
• It is also a core mod that affects vanilla leaves. After inspecting their source, if we were to implement this config option, passable leaves would have no affect on our leaves.

That's unfortunate.
A config in native TFC would be good then if none else.