Systems and methods for using design and/or constraint information in selecting, editing, creating, and managing content for multiple operating environments. For example, an image editor feature of a content management system can receive constraints and/or design requirements identifying specific image sizes that are needed for offering a piece of content on one or more operating environments. This information may be used to guide or restrict a user to select appropriate image portions. A selection marquee, sized based on the constraint information, may be positioned on a displayed image to select an image portion to use for that particular image requirement. The marquee size enforces the image constraint. Design and constraint information may also be used to inform selection, editing, and creation of other constraints and other types of assets, including, but not limited to, text and video assets.