After upgrading to FF 27.0.0.1 and also to NoScript 2.6.8.14, and when viewing pages on which scripts are refused , and NoScript is set to display a notification (message about blocked scripts) at the top or bottom of the window, and opening an image larger than the window display area, the problem can happen. When clicking on the image to see it (part of it..) full size, the image will open withoutthe noScript notification , then right away the notification will appear, reducing the image size a little. This makes it appear as though the image size increased until it 'bumped' against the window frame, then rebounded to a slightly smaller size as the NoScript message appeared.