Great Extension, 1 issue Rated 5 out of 5 stars
This is a great extension to enhance the look and feel of the Lightening calendar add-on - especially if you use or have used Outlook. From my perspective, it provides a professional look and feel to Thunderbird/Lightening with smoother color gradients and various interface tweaks (e.g. calendar tabs). This extension puts Thunderbird/Lightening up there as a contender with the overpriced MS Outlook from an aesthetics perspective.
One issue I have noticed with Thunderbird 6.02 and Calendar Tweaks 3.0 is that it breaks the "Delete" button if you add it to the Mail Toolbar. I always do this as it makes it easier for me when doing bulk activities. If I disable this extension, it works again. I have contacted the extension developer to bring this to his attention. I mention it hear to help others thing they have lost their minds. LOL
Regardless, this extension is deserving of a 5-star rating. It does what it says it will do and except for this one issue I have experienced no problems when this extension is installed.
Not an issue with Calendar Tweaks
After further investigation, this reviewer has confirmed that the reported issue is NOT caused by Calendar Tweaks.