It’s hard to express.
I just want to reset the size of the image in each widget to make them display maximum.
I call this function while one button was pressed.
If you don’t want to reset the offset, but want to change the zoom, right-clicking and dragging up and down will allow you to zoom in or out to any degree you want. If you are concerned with keeping multiple slices in sync with one another in terms of relative physical scaling, linking the slices together (making the rings just below the pressed push pin toggle to linked rather than unlinked) and then changing the zoom on any of the slices will cause their scaling to sync. Generally I find those two controls cover most of my use cases well enough. If I want the image to be exactly filling the slice, then I click the center button and then scroll the offset back to where I want to be, either by spinning the scroll wheel or by holding the shift key down and moving the cursor (no click) to the region I want to focus on in another slice. Holding the shift key down centers all of the slices on the point your cursor is over (if the meaning of that isn’t clear, just give it a try, it is easier to understand in action that it is to describe it).