I'm using DO for some time now, and since I had to install everything from scratch after a HD failure, I'm missing the little search windows from DO. Clicking on search in the righthand-mouse popupbox, opens the default search windows from Vista.
This is easy to add back, but in case you don't know, you can already access Opus's Find window/panel in a couple of ways.
To open the standalone Find Window, you can push F3 or Ctrl-F, or use File->Find.
To open the Find Panel, which is part of the lister and much nicer in my opinion, you can use Tools->Find Panel.
Of course, you can open both of these things via whatever hotkey, toolbar button, menu item or context-menu you like.
Going back to the real question that you asked, if you want to be able to right-click a folder and see an item to use the Opus find tool on it then you need to do the following:
[ul][li]Go to Settings -> File Types.[/li]
[li]Double-click the All Folders type near the top.[/li]
[li]Select the Context Menu tab.[/li]
[li]Click New....[/li]
[li]Give the new menu item a name (e.g. "Find" or "Search using Opus").[/li]
[li]Set the type drop-down to Run an Opus function.[/li]
[li]Enter this as the command: Find IN {allfilepath$}[/li][/ul]
As a bonus, if you select more than one folder and right-click you can search all of them at once.