I want to search the entire file system for a file.

Using gnome, I click on the filing-cabinet icon on the desktop and a file-manager program opens.

By "checking" go/search_for_files, a search toolbar opens, and I type the name of the file, then press enter.

As a test case, I search for a known file, but the file manager doesn't find it.

A search results toolbar appears with location and File_system drop down windows, additional search criteria can be added using the + (plus) sign.

Pretty simple, but I can't find an option to search the entire partion for a file.

What am I missing?