My Calendar version 1.7.0 is about to be released. This version contains a large number of significant changes, some of which may have consequences for your existing installation. I have taken every precaution I could, but there are aspects inherent in the automatic update process which cannot easily be tested thoroughly in advance. In preparation for the release, I strongly recommend that you make a copy of your current styles and note the settings of the Upcoming and Today’s Events widgets.
Both widgets have been entirely replaced with the WordPress Multiwidget class, which will allow you to use multiple individual instances of your widgets.
The stylesheet editor is moving from a database-driven editor to a file-based editor, which will increase the cacheability of the plug-in styles, improving performance of your site when using the styles. This also comes with the ability to choose between several different stylesheets.