Double-clicking on various tree view items results in the following actions:
On namespace or any type of class - expanding/collapsing respective subtree
On manifest, field, method, event, property - showing disassembly of the item in a separate window
On .class info item - showing partial disassembly of the class in a separate window
On extends info item - selecting the parent class (if present) in tree view
On implements info item - selecting the implemented interface (if present) in tree view