in the 'Search Messages' dialog there are 'open', 'file' and 'delete' buttons. i think we need some other actions like 'select' or 'set flag'

The search window has the problem that it is missing a lot of commands you might want to do for the found messages (forward, print, ...). The recent "Go to folder" function helps here, because now you can perform the operation in the real message window with all commands available. It is still quite tedious to move back and forth between the search window and thread window when you have more than just a couple of results. Quick search doesn't have this problem, since it shows the results in the thread pane. However, it has only some of the search criteria available. To get access to the rich search criteria with the ability to view the results in the message window, Flag command should be implemented in the search window. Then you would be able to flag all the search results, close the search window and see the results in your message window (sorted by Flag). This would be nicely augmented by "View|Messages|Flagged"... I would go as far as not adding any more "missing commands" to the search dialog after this, but to make it show its results in a message window some day.

Attachment 56403 [details] [diff] contains a patch I have been using some time to implement both the Flag column to flag individual messages and a Flag button to flag current or selected messages. Attachment 56404 [details] contains a screen shot of the visual changes.

mass re-assign.

*** Bug 99995 has been marked as a duplicate of this bug. ***

Bug 66970 would pretty much cover all the bases.