Not super serious, but when you're creating a document, paste an image in that is larger than the window, you get a horizontal scroll bar so you can move to the right side of the image.
However, if you try to grab the blue square at the top right or bottom right, the vertical scroll bar is on top, so you can't make the image smaller (tested in Firefox at least). Instead you have to adjust from the left side, which doesn't resize quite as easily as the right side…