I'm using Nimbus Screen Capture add-on with FirefoxDeveloperEdition 40.0a2 (2015-05-28). When making a screenshot, no matter if Selected area, Entire page or Visible part of page, clicking Save as Image doesn't do anything. I can Copy to clipboard, though. So this helps as a workaround. Nevertheless - why isn't Save as Image working anymore? It did - once.
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