Toggle between automatically and manually processing between each step

[b321gonzo]

I'd like if I was able to manually process between each step. For example in step one, when changing resolution and resizing the crop, every adjustment I make I have to wait for the whole thing to process. It starts of with the image croped in the middle, so I drag the crop window to the top left corner in which it starts processing, and then I resize the window and it has to process again.
Any adjustment anywhere it starts to process automatically. I want to make all my adjustments to a single step before it processing.
I thought some kind of toggle switch would be helpful.