OS: Linux
When saving an image and using the pop-up window that prompts for the format options (quality, compresison, etc), clicking "Cancel" should cancel the save operation. However, if you click "Cancel" it still saves the image file!

Only clicking "Okay" for the format options should save the image. However, even if you click "Cancel" it still saves the image.
Even clicking the "X" close button in the top-right corner will also save the image.