When trying to use a Dashboard widget recently, I was not able to pull up a contextual menu in a text field, where I thought I should be able to do so. Well, it turns out that the menus are in fact there, but there is a bug in Dashboard with accessing them.
So what is the problem, you might ask? Well, if you're working with one of the Apple-shipped mouses, or the trackpad on a laptop, you're not likely to see the issue, because if you Control-click to get the contextual menu, it will appear as expected. If, like me, you prefer to use a more functional mouse, which Apple generally supports very well, the contextual menu does not pop up with the second mouse button as one would expect.
[robg adds: I don't know that this is a bug in Dashboard; it could be something related to how the widget was coded ... but if you're having trouble with a certain widget's contextual menus, remember to try a good 'old fashioned' control-click...]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20050727070352803