Such dialog is shown when "Find Opened File(s)" command in Tools menu is performed. Dialog is resizable.
Edit Box contains mask for files and DLLs searching. Enter mask and click "Search" button. Mask can contain wildcards.
"Search as Sub String" check box if checked means automatic adding wildcards to sides of search mask. So ",dll" will be used as "*.dll*".
List Control contains search results. When you select row then automatically corresponding process in "Processes Pane" will be selected.