Example collections in my Steam library:

Favorites (collapsed)

• Batman Arkham Asylum
• Dark Souls
• Resident Evil 4

Installed Games (expanded)

• Batman Arkham Asylum
• Dark Souls
• Resident Evil 4
• The Forest

Steps to reproduce:

• Collapse the Favorites category
• Open any game that exists in both Favorites and Installed Games (e.g. Dark Souls) so its info shows in the right pane
• Navigate to the Store, then back to Library

Expected: The game is highlighted in Installed Games, since that category is already expanded and the entry is there.

Actual: Favorites auto-expands and highlights the entry there, even though the category was deliberately collapsed.