try this reproduction:
1.) Run a 'clean' XnView MP 0.48
2.) Open a Video file to watch in the XnViewMP 'view mode' (I tested with a .wmv)

3.) Press 'next/prev file' command to go to a next or previous file in same folder (works as normal

4.) ...Hmmm but now go now click on the Menu bar for either the 'Files' 'Tools' or 'Help'....
5.) ..Then now obsevre that the ability to Next/prev a file is greyed out (a bug) as well as other greyed out items
please investigate and fix!
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Also the ability to close a tab with video playing is currently not working, this must be fixed too....
1.) Run a 'clean' XnView MP 0.48
2.) Open a Video file to watch in the XnViewMP 'view mode' (I tested with a .wmv)

3.) Now try to close the tab (tab close button OR CTRL+W)...
4.) ...Tab cannot be closed

=So here the only way for me to close the tab here was to open an image from "Recent files" which replaced the tab
=Also any file item opened from "Recent files" during a Video playing/stopped should of course open in a new tab
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Related topic: http://newsgroup.xnview.com/viewtopic.php?f=62&t=25752