I think there are three, large-screen, small-screen and thumbnail.
|Large Screen||This is the Desktop/Laptop user, the screen has plenty of room to view the work and be surrounded by tool boxes. Major design work can be performed in this environment.|
|Small-screen||This is the Netbook/Pad user, the whole screen is mainly given to the work, with a small menu/toolbar to a short side of the window. Minor amendments to the design can be performed in this environment.|
|Thumbnail||This is the display on the machine. It requires a small colour image and the file-name to be displayed.|
The preview-image allows file operations to be applied to the correct design, I hope some sort of service would allow a design to be copied to a (say) JEF folder to have the design converted on-the-fly.
Design of the User-Interface
Luke Wroblewski tells us  we need to consider:
- Interaction Design - how on screen objects move in response to the cursor
- Visual Design - information is presented in an engaging or understandable way
- User Research - study how the users interact with what they see in the application
- Copy-writing - choose wording suitable for your audience or users
- Information Architecture - providing the necessary information and suitable presentation for the user task
- Conventions - existing learned behavour from other applications
- Proximity - related functions are located near to each other
- Muscle Memory - the menu item or button is always in the same place, clicked without looking
- 1: Luke Wroblewski, An Event Apart: Properties of Intuitive Web Pages, 2012, http://www.lukew.com/ff/entry.asp?1498