Desktop Registry Settings (Compact 2013)
Your shell can display specific desktop wallpaper by retrieving the current wallpaper registry values from the HKEY_CURRENT_USER\ControlPanel\Desktop registry key.
To specify the name of the wallpaper bitmap to retrieve, set the HKEY_CURRENT_USER\ControlPanel\Desktop\Wallpaper registry value to a string that is the path to the bitmap. The following registry key example shows how to set this registry value.
To specify whether to tile the wallpaper bitmap, set the HKEY_CURRENT_USER\ControlPanel\Desktop\Tile registry value. Set this registry value to 1 to display the wallpaper bitmap as repeating tiles, set to 0 to display the bitmap normally. The following registry key example shows how to set this registry value.
Finally, call PostMessage to post the message to all top-level windows in the system, including disabled or invisible unowned windows, overlapped windows, and pop-up windows. This call is shown in the following code snippet.
PostMessage(HWND_BROADCAST, WM_SETTINGCHANGE, SPI_SETDESKWALLPAPER, 0);