If that is the case then the folder layout is very confusing, shouldn't objects and events be subfolders of their respective layouts? How do I tell which data object is being used where? There is no way to determine this that I can see...
Yep the current display is a bit confusing.
A better display (as well as global objects) will be eventualy brought to C2 (it is part of Ashley's long to-do list)
For now, you should know and remember which layout you added the object to.
In that respect, I'd suggest you to make folders in the "Objects" or "Projects" tab and sort your objects depending on the layout they belong to.