Don't pass some mouse events to items
ItemSync: Fix item and file encrypt/decrypt (only loaded formats)
Use layouts inside item widgets
Don't set style on web and rich text items (too expensive)
Don't check clipboard data if it belongs to any session

Clipboard synchronization when running multiple sessions makes the
sessions fight over clipboard.

Additionally if user selects item in one session it's not very useful to add it
to other concurrently running sessions.