Here's a video showing off how and when to use it (thanks to Matias for letting me use the file from the blog for testing :)
From the video description and commit log:
This operator helps fix up this mess by taking the selected strokes, projecting them to screenspace (i.e. "flattening" the strokes back on to the screen), and then putting them back out into 3D space again. As a result, it should be as if you had directly drawn the whole thing again, from the current viewpoint, but without losing the pressure/strength info.
Unfortunately, if there was originally some depth information present (i.e. you already started reshaping the sketch in 3D), then that will get lost during this process. But so far, my tests indicate that this seems to work well enough.
* Why don't we just have a way to lock the 3D cursor to prevent this problem in the first place?
I tried doing this a few months ago, but ultimately some of the other devs didn't like it, and the commit was reverted. If anyone is interested and can make their own builds, I recommend "cherry picking" this commit for use in your own builds. That's the beauty of open source - the code is there in the Blender repo (though removed), and you can hack stuff like this back in if you so desire :)
* What other alternatives are there for locking the 3D cursor?
Personally, I've been experimenting with a number of keymap changes to make Blender easier to use for Grease Pencil work. In particular, there are 3 things I'd recommend if you're doing a lot of GP work:
1) Remap the 3D cursor keymap from "ActionMouse" to "P + ActionMouse"
2) Add an extra keybinding for starting/stopping playback to Spacebar (instead of just Alt-A)
3) Rebind Operator Search to "Ctrl-Spacebar"
4) Disable or remap the "Ctrl-Spacebar" hotkey for doing stuff with manipulators. Since I never use those blasted things, I just deleted the keymap entry :)