UI: Preview of a newly selected document is not shown after opening many documents (eg. 8)

• when clicking a document a preview tab is opened at the right side. When many documents are selected, the preview of a newly selected document is not visible. You need to close another document first.
• possibly performance impact on server when lots of preview tabs are open

The solution is not easy. Some alternatives:
Show a msg similar to the max 5 edit tabs
Close the least recently used tab
Similar to FF, make the tabs smaller
Show a scrollbar.