Integrated development environment IDE (999), method and computer system for developing user interface documents. An editor (104) is used for editing a user interface document. An adaptation engine (105) generates device class specific representations of the user interface document. Each device class specific representation refers to a respective device class. Device class dependent tools (120) of the IDE (999) are used for generating device class specific information and providing it to the author. Device class specific information can be information about the complexity of the user interface by device class provided by a complexity indicator (121), information about how many pages are generated for which device class provided by a device class dependent view (122) or information about the layout for various device classes provided by a frames layouting view (124).