Masks

Hi all, I haven’t bought the software yet (I’d really like to) because this is about the 5th lot of Mac slideshow software I’ve looked at. It seems none will do what I want.
I want to create professional looking slideshows of flowers and flora native to our area. I am not a professional it is simply a hobby.
I want to create my slideshows with a black mask in (say) 16x9 size with (if possible) a thin white key-line.
When viewed on computer, television or projector I would like the slideshow to take place INSIDE the (fixed) mask including animations etc.
Is this possible with FotoMagico? If so I haven’t been able to find a way to achieve it.
Thanks in advance.

do you want this mask to be there on every frame?

If so, create a semi-transparent graphic that looks the way you want it in a graphics app with a transparent cutout in the middle and save it as a png. now go to Slideshow (Menubar) > Settings and use this file as a watermark image. Now position it on top of everything.

You can also create an image mask for each slide to create these individually.