How do I export a single frame from iMovie 10.0.3?

I might end up resorting to a screenshot, but I do not know
the movie's resolution, and would like an image at actual size.

I have tried lots of methods that came up when I searched online.
The only one that worked for me was a screenshot, but that runs into the size issue.


Some sources suggested various options under the "Share" button, but none of those options come up when I click that button. ​ ​ ​ ​ ​ ​ ​ The options that actually show up for me are
Theater ​ and ​ Email ​ and ​ iTunes ​ and ​ YouTube ​ and
Facebook ​ and ​ Vimeo ​ and ​ CNN Report ​ and ​ File .

Some sources suggested a "right-click", or showed a menu being brought up looks
exactly like those that come up from right clicks. ​ ​ ​ ​ ​ ​ ​ However, I have tried button+click
for each button from among ​ fn , control , option , command , shift ​ , ​ ​ ​ both on the
normal display and the full-screen display, and none of those brought up any such menu.

Some sources suggested starting by copying a small segment of the movie into a new project.
However, I cannot figure out any way of creating a new project, and although I can easily
create a new event, I can't figure out any way of getting a significant part of the window to
correspond to the new event, whereas the sources I mentioned in my previous sentence
show that having been done for the projects. ​ If I instead drag the segment over
the name of the new event and let go, then it moves the entire movie to the new event.

Other than just taking a screen-shot without knowing whether-or-not
the screenshot is at the actual resolution, is there any way to
extract a single frame from iMovie 10.0.3 that actually works?

(In particular, a way of playing it at actual size that lets me advance frame-by-frame would suffice.
However, bear in mind that I do not know the actual size.)

In my copy of iMovie (v10.1.6) you can do this easily:

File > Share > Image...

And it will prompt you to save a jpeg of the current frame.

Alternatively export a high quality video ("Theatre" ?) go to the frame you want to capture and select Copy from the Edit menu. Open Preview.app and select File > new From Clipboard and you have your screen capture.