Is it possible to make some sort of control that checks if a user is trying to add an image with a width of more than 500px? I have a section with a blog, and if the user adds an image using the “Insert image from file”-button it cannot have a width of more than 500px! Or the “entire” page structure fails (to the right there is a “menu”-section with links to archived posted entries from passed months which is pushed down underneath the newly posted blog entries, if the image is wider than 500px). Is it possible to control this anyhow? I really don’t trust that users will read and follow instructions if that’s the only thing I’ll do. This check should only be activated at this section of the homepage. Any suggestions?