This post is more of a feature request. Certain tools/plugins allow a “Preview” mode before an operation is executed on an image, a very useful thing. Unfortunately the dialog box takes exclusive focus, and the user cannot do basic handling, specifically zoom/pan functions. Sometimes the effect of an operation can only be seen on a zoomed view across several areas of the canvas, far beyond what a screen can reasonably display.
Current workaround is to apply the operation, inspect after the fact, and undo if not suitable, which defeats the purpose of “Preview”.
I can see individual tool/plugin authors adding a up/down/left/right buttons for panning, and slider or input box for zoom factor but this seems something that can be better handled if all subcalls could can temporarily relinquish focus back to JUST the image in question, provided the tool/plugin gets focus back, and the focus transfer is sandboxed such that no operation occurs that would de-stabilize the tool/plugin or ImageJ (or, you know, rupture the space-time continuum as we know it, because that would be bad).