Scratch

Bluey55, are you asking the Scratch team to add a "flip" block to the scratch language?  If so, could you be more specific about what *exactly* the block would do?

Or are you asking how to make a character do a flip?
I showed one of the 5th graders in Tech Club a simple way a few weeks ago.
It consisted of two scripts.  One script did a slow rotation:

repeat 20 times
    turn 18 degrees
    wait 0.1 seconds

The other did a pair of glides:
    glide 1 second to   Xposition+50  Yposition+100
    glide 1 second to  Xposition+50  Yposition-100

You can play around with the times, the amount to turn, and the amount to move to get somewhat different effects.  Changing the rotation center for the sprite can also change the effect.

This is not a physically realistic flip, but it works fairly well for very little code.

Oh, I didn't mean to confuse anyone with my 'flip'-tutorial, just wanted to give a very simple introduction to the Scratch source code for those who are interested in it. I'm very sorry if someone mistakes this somehow as a 'hidden feature' of Scratch. It is not! I just chose a particularly silly and easy example that would not add any novel feature to Scratch, because I didn't want to spark a discussion about the usefulness of that example block.

Also, there are no experimental features in that tutorial-project, it's just a (very simple) standard slideshow.

Bluey55:
If you want to mirror a sprite's costume or a background of the stage (like my tutorial shows) the correct way to do it in Scratch is to just make another copy of that particular costume / background, and use Scratch's paint editor to flip it horizontally (then acknowledge it by pressing the ok button). Now you have two costumes, an original one and a 'flipped' one. You can then tell your sprite to just switch to the flipped costume, or the stage to switch to the flipped background (and back again).

In other words: There is absolutely no need whatsoever for a "flip" block in Scratch, because you can already accomplish all it does with the existing Scratch blocks, and much easier so.