Flipping Animated GIFs

[Richmond]

So, I am working out something fairly babyish for one of my 
"introduction to programming"
nonsense in the Summer and have a stack that has the dimensions:

1044 x 788

it has a transparent graphic with a 2 pixel black border of dimensions 
1024 x 768

[this is to explain to kids what is "on-screen" and what is "off-screen"]

and an animated walking stick figure called img "MAN" (animated GIF)

I plan to use the arrow keys on the keyboard to move "MAN" around.

HOWVER, I don't really want "MAN" walking backwards sometimes, so 
decided to FLIP him
like this:

flip img "MAN" horizontal  (grammatically a bit dicky, but coding-wise 
acceptable)

when I do that the animation stops . . . not good at all.

So . . . questions:

1. Is there a way to, while flipping my GIF, ensuring it keeps animating?

2. Or, am I going to have a leftward facing version and a rightward 
facing version and muck around with
visibility?

Richmond.