Cancelling a progress bar cancels everything downstream

[davidh]

two preliminary facts:

cancel a running transformation by cancelling its progress bar -> you get the red error output thumbnail
dblclick the red output to recall the hidden dialog and cancel the dialog -> the output reverts back with no changes made (still it keeps the title of the cancelled transformation)

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Now, let say I have two or three outputs downstream, one of which needs a lot of resources (Precise Gausian Blur, Zoom Blur, etc.)
PWP makes it possible to return to any output upstream and run it again with other settings. So it can happen that cancelling a transformation progress bar of an image somewhere upstream disables all the outputs downstream -> displays them as red error thumbnails.

To solve it, it needs to dblclick one after another the error outputs and cancel the dialog. Or to close the offending error output.
Another solution might be just to dblclick (and cancel) the offending thumbnail, and then click the Refresh button.

But even better, what if cancelling a progress bar did not turn the output to a red error thumbnail but made it the same as its input? Any transformation on it would be rolled back and no outputs would be impaired downstream.