https://i.gyazo.com/9f9ed8bc591e8afdb0dab24c69cbdbd8.mp4
Editor is working exactly as intended, here is what I did in that short clip.
1. select panel you want to edit
2. select side of the panel you want to move (WASD), I selected bottom one with S, hence my character moved back
3. Click left or right button on your mouse to increase/decrease anchor value of specific side
4. Press R to go back to edit menu
It might be bit confusing on first glance but that was the only way how to make it work with keys in game.