VolatileImage currently has no means to help the user support multi-
monitor situations. The problem is that VolatileImage objects are inherently
tied to the device on which they were created (e.g., the video card of
a particular display on Windows). When an app asks the VolatileImage to
copy its contents to a different device (for example, if the app window
moved to a different monitor or the app attempts to use one back buffer
for several windows), this operation could fail but there is no way for
VolatileImage to tell the user why it failed or what to do about it.