Unable to use 'U' unity shortcut while popups are open

Issue description

Whenever opening a window such as the shipyard, unable to use the 'U' keyboard shortcut for unity. All of the other shortcut keys seem to work fine.

Reproduction steps

1. Open save
2. Open popup window by selecting a building (any work so far that I have found)
3. Observe 'U' key not working

Game version and build number

v0.7.2a (b433)

Operating system

Windows

Attachments

Unity_Key.save

Files not imported: Unity_Key.save

Also if I pin a big sorter windows I have same issue.

The U key can be used as a shortcut to do a quick-delivery for the currently selected building. We also improved it so that pinned inspectors are ignoring the key.