Issue: When I add a Quick Metadata search in the sidebar of Home Page, the Quick Metadata Search Box is not showing anything, its blank.
Resolution: Add WhiteListed Domain for VisualForcePage inline Frames under Setup | Security Controls | Session Settings.
PS: View Metadata Search, Salesforce quick search app on Salesforce AppExchange: https://appexchange.salesforce.com/appxListingDetail?listingId=a0N30000009wgF7EAI