Nested pre-comp doesn't show up/ timeline with unknown selector

[Emanuele26903131yn72]

Hello!

I have a pre-comp (so to work easier with paths) with a character that I have to animate in relation to an object that stays in the main comp (a girl that has to enter an airplane: girl layers are in pre comp, airplane is in main comp and it's itself a pre-comp).

I need, to animate, the reference of the plane in the character pre-comp as a guide layer.

1) how do you fix the comp space/ layer space issues in this kind of situation ? (if I simply copy the aircraft pre-comp into the character pre-comp - both pre-comps are in the main comp - , the positioning of the 2, initially nicely placed comps in the main comp, gets screwed up in the character comp because of the different referenced coordinates. I usuall parent the reference layer before importing to the comp, but it looks just like a workaround and not the proper way. 

2) sometimes (this time for instance) I just don't understand how things works. The aircraft pre-comp is not showing in the character pre-comp, it is like grayed out and there is that strange indicator made of the double arrows with vertical ends instead of the normal one. I tried hard to find out what that means but no luck! It looks like the aircraft pre-comp is not displayed because is somehow out of the timeline, but there is no anchor point, not even the bounding box of the comp itself and I don't know what to do to make it appears.

I hopw I was able to explain the situation

Circled in red the unknown timeline selector and the pre-comp not showing up, is there but is actually nowhere...

Thanks a milion!

[Mylenium]

The double arrows are the pan behind tool which also doubles as an interactive layer trim and you see it because your layer has inactive/ trimmed areas, hence the faded appearance. As for your structure conundrum - create a third composition that acts as a guide layer. This can be some simple graphics that tell you where your reference point for the aircraft door and other things are. Use this reference comp in both the actual aircraft comp and your character animation while keeping the comp sizes themselves consistent and the same.

Mylenium

[Emanuele26903131yn72]

Thanks a lot, that makes sense to me. I was struggling to understand how to trim the layer, since its like almost non existant when is inactive for the whole duration of the comp. But now I figured out that I could use the expande/collapse duration switch and it worked to bring it back from the secret spot out of the timeline where it was hiding. 

Is there a way to find the name of these tools, when we don't know them, so to look directly in the adobe guide?

I was trying but since I had no clue that it was called 'pan behind tool', all my searches brought to nothing...

Thanks again!

[Mylenium]

It's unfortunately all buried in the respective help pages and often only mentioned in passing like this one:

https://helpx.adobe.com/after-effects/using/selecting-arranging-layers.html#select_layers

The help has been ripe for a complete rewrite for years, but sadly Adobe never commit to it...

Mylenium 

[Emanuele26903131yn72]

Thank you Mylenium