Details shows you useful navigational information to quickly browse between connected components & glyphs.
Content within the details are only shown if they exist; here is what you can expect to see in there :
Usage as a component
Shows how many glyphs are currently using the selected one as a component, and allow you to batch select them using the 
Select all button.
Decomposition
The glyph decomposition is documented for a subset of glyphs within Unicode. If they exist for the selected character, you will be able to browse through them from here.
Note that you can use the
of the
Glyph components to quickly create a composite glyph from its known decomposition.
Alternatively, use +to create a new glyph along with all of its dependencies, and bootstrap components structure in one swift click.
Relatives
Relatives shows a list of the direct relatives (as per Unicode, single depth only) of the currently selected glyph, allowing for great discovery and making it easy to spot & find associated glyphs you might want to support.