In going through the themes in the WPF Themes project on CodePlex I've encountered many inconsistencies. Sometimes these inconsistencies are annoying and other times they require much more complicated fixes. All these issues are instructive because they teach us things to be aware of when building our own themes or even our own templates.
I've written about some of the more complex issues I've encountered in the past. Today I'm just going to talk about one of the more simple problems. Some themes in the WPF Themes do not properly display the access keys. The underscore used to indicate the key was being displayed instead of removed. This is a simple problem to fix. ContentPresenters have a property RecognizesAccessKey. If this property is not set, it defaults to false and the access keys will not work. Writing RecognizesAccessKey="True" will make the access keys work properly.
I would have preferred the default for this property to true. In the general case I want the access keys to be active. An even better solution would be if there was a global way to specify the default for it. Using access keys is usually what you want to be application wide and it'd eliminate little presentation bugs to if this was possible. Its easy to forget to set this property on a ContentPresenter which can manifest in hard to find locations. Its an easy problem to fix, but annoying when you discover it.