Explain your idea

Allow the Engineer's Handbook to search while in a specific page's topic. You can currently search while on the main manual page or in a subcategory, but when you attempt to search something while within a content page, you will not be able to do so. This suggestion requests that this be changed.

In Main Page:

In Sub-Category:

In Content Page:

The search results replace the page content.
When you are searching in an entry, you'd lose the entry itself, and entries are a lot more complicated than the lists of page / category titles.
That's why this is not possible.