All editor dialogs have a line above the dialog-button-box over the whole width. Only the Image Properties dialog has this line only below the "Advanced Edit.." button which looks like a unwanted artifact. This line should also go over the whole width.
Created attachment 8807942 [details] [diff] [review] imageDialogSeparator.patch The separator from EdDialogOverlay.xul is too short because the Image Properties dialog show the image preview beside of the AdvancedEdit box. We need to draw our own separator to fix this. The other solution would be to move the image preview box above the AdvancedEdit box, but I think beside looks better.
Comment on attachment 8807942 [details] [diff] [review] imageDialogSeparator.patch Thanks. r=jorgk.