How to add an "Open With ..." to context menu

When I double click on a .TIF file it opens in the DOpus viewer. I'd prefer to have it open in Photoshop, but have an option in the Context menu to open it with the DOpus viewer. If that's not doable, I'd like to add an option to the Context menu to open the file in Photoshop. Photoshop does show on the "Open With" menu, but I'd like to avoid having to go to that menu. Is there a way to add the DOpus viewer as an option on the Context menu for .TIF files, and if not, is there a way to add an "Open with Photoshop" option on the Context menu?

Go to Preferences / File Operations / Double-click on Files and check Use internal picture viewer for then select unregistered picture file types from drop down.

To add the context menu for DOpus viewer open File Types dialog and double click the Images group, then the context menu tab. Insert a new action to run the command:

Show

Edit: This will open every (registered) image though with the default program (which in your case probably is photoshop). If you only want .TIF images to have this behavior you'd probably need to change the other image types individually in the File Type dialog to run

C:\path\to\dopus\dopusrt.exe /cmd Show

The standard Windows built-in way to show "Open with..." is to SHIFT Right Click on a file. (Works in Explorer too.)
This way it only shows when needed. Although most of the times that menu item is visible anyway, whether direct or under a sub menu called Open with.
When you choose Open with... you have the option to set the selected program as the default.
Also you can leave DO set to handle All recognized pictures.

Thank you for the reply! Following your directions I was able to add a command "Open with DOpus Viewer" to the right-click context for image file types. I then set TIF files to open with PS. So when I double click on them, they open in PS, but I also have the option in the context menu to open them with DOpuse Viewer. For some reason that I don't understand, if I double click on another image type (say JPG), it opens with the Windows Photo App, but I can open it with DOpus Viewer through my new menu action. I appreciate the help!

If you set the viewer to only handle unregistered picture file types then it won't handle JPEG or other types that are registered to pen with something else already; only anything left over that doesn't have a program associated with it.

If you want a mixture of some types using the Opus viewer and others using something else, you can do that. The best way to do it will depend on whether you want the difference to only affect Opus, or to affect everything.

To override a file type to use the Opus viewer only within Opus, open the file type and go to the Events tab, then edit the Left Double-Click event so that it runs the Show command.

To override things outside of Opus, right-click them and use the Open With menu to change the default program and select d8viewer.exe from the Opus program files directory.

(If you want both, it can make sense to do both at once, as then double-clicks within Opus will pass more information about the next/prev list of files to the viewer. e.g. So they will be sorted the same way they were in the file display, not always alphabetically.)

You can also do things the other way round: Set Opus to use the viewer for all recognized images (not just unregistered types), then override just the double-click action for TIFF file so that it runs Photoshop instead.

Thank you so much! This is really clear and gives me exactly the understanding I need to know how to handle file types within Opus. I'm gradually building my knowledge of Opus; I truly appreciate the help.