Rated 5 out of 5 stars
Beta3 prevents attachments from being opened. Stick with the v1.2.4.
Edit: Tested 1.4.0 Beta1. I can confirm this issue is fixed (either by author or tbird update.)
Upgraded rating to 5 stars. Mozilla should have made this a feature.
Probably a bug core bug of Thunderbird which was fixed in 3.1.5
Subject says it all: This bug seems to have been disappeared with the release of Thunderbird 3.1.5. Could you please check.