The central feature of any UI is the window. In Windows CE–based platforms with a graphical display, the window is the rectangular area of the screen where an application displays output and receives user input. However, even applications running on devices that lack a graphical display require windows to receive messages from the OS. To help manage the windows used in an application, Windows CE supports the Win32 API UI, tailored for the smaller display size of typical Windows CE–based devices. The following table shows the similarities and differences between the Win32 API UI and Windows CE.
Win32 API UI |
Windows CE |
| Owned windows | Full dialog box support |
| Sends nonclient messages to applications | Not supported |
| Client area | Maximum area to support a command bar in client area and controlled by application |
| Multiple-document interface (MDI) | Not supported |
| Bitmap menus | Not supported |
| Cascading menus | Supported |
| Owner-drawn menus | Supported |
| Icons of any size | Supported |
The OS controls how the nonclient area is drawn and managed; Windows CE does not send applications messages dealing with the nonclient area of the window.