You can extend the Lotus Notes search bar with a little coding but you can also create a pretty easy search engine based on Text Selection using Widgets. I often get emails referencing my blog or something on Planet Lotus so these two widgets come in handy for me. I created two widgets, one to search my blog and another to search Planet Lotus from a text selection.
Here is a video showing me creating the Balfes.net widget:
testing the comments with no user account.
Any chance you done this for a Domain search using the Domain catalog?
That is part of Notes 8.5.1 might even have been in Notes 8.5 but I do know its part of the product in Notes 8.5.1.