I was trying to upload a Windows image on Colo, and (because it was gonna take some time), I switched tabs.
Checked on it after a while, and still saw the 'Upload image file' spinner moving, but no progress on the bar whatsoever. No warnings eithers. Opened Developer tools and and saw that there was indeed a failure.
In this case, it would be good to leave the warning static OR show the user that the progress in the Image upload has stopped.
