IntroductionVersion 0.7 of the Googlebar will contain a new feature called "GooglebarExtras", which will allow users to add any extra buttons etc to the Googlebar and keep them in their own separate files. This is in response to the request of a number of power-users that we add a variety of new buttons to the toolbar, which, while useful, might not be of general interest for the average user (for example, a w3 validator service button). This is mainly a feature for power-users, rather than something we plan to actively support, but if you like your addition, please feel free to submit it to the project mailing list and we'll try to post it to this page when we have a chance.
Caveats (as in, "There's a catch")While these files can be packaged up into an XPI and used to install the features with every new release (rather than having to make all the changes and additions by hand every time, which makes it harder to modify the Googlebar for personal use), we are not re-inventing mozilla extensions. For starters, only one copy of the Extras files can exist at a time. You can add all the things you want to that file, but if you then install a separate XPI containing someone else's feature, you'll lose what you have- your files will be replaced by what you just installed. And second, while it may just be possible to add mouse gestures and email encryption to the Googlebar through mozilla and this feature, that's not the point- the point is to make it easier to add buttons, and if you want the features of more than one extension, you need to be able to edit these files and combine them yourself.
UpdatePackaged examples of a relatively late model Googlebar(version 0.9.0.04) into 2 complete installers. They are named customizerKit-original.xpi and customizerKit-enabled.xpi, just so there is no mistake about what they are for. You can install either one, hack away, and when you are finished, update with one of the standard googlebar installers everything will be overwritten.