You can invoke a right-click menu by the "Application" keyboard key (resides between Ctrl and Alt keys on my keyboard).
I didn't know that
In my case, it's the key between AltGr and right Ctrl. I think the icon's meant to be a menu. I always think it looks like a stylised petrol pump
What user-defined options should be available in your opinion?
ChoiceEditor works like an extension-sensitive context menu. You configure your own choices. In my case, for example, if I have Total Commander's cursor on a .txt file and press F4, I get a menu like the first screenshot. On the other hand, if the cursor is on a PDF file, I get a menu like the second screen shot. Some items appear on both menus because I configured them to be available for any extension, "*"
I'm not sure about what do you mean by "send plain filename". But MultiFind Pro already adds several useful command to context menu: "Open File name" and "Copy file name".
I'd like to copy file name only, without path; copy file name with path, as Multi-Find does now; and copy file name with full UNC path. I don't need the last so much now, but it would have been useful when searching the network at work.