The HTML Tags toolbar allows you to quickly enter HTML tags into the Notes field. Those HTML tags are always shown as HTML tags, they are not used for formatting text within Tasks Jr..

So what is it good for?

It ties in with the ability to post to a blog from within Tasks Jr.. There are two scenarios where this is commonly useful:

1. If you are using Tasks Jr. to store drafts of your blog entries.
2. If you are using Tasks Jr. in a corporate environment that uses blogs for internal documentation and communication, being able to blog easily about something you are working on is quite handy.