#378 rdesktop and backing store

[Martin Wheatley]

We believe the use of the X11 macro DoesBackingStore() in rdesktop is incorrect.

The X11 macro returns information about when the X server might use backing-store but just because it has the value 'Always' doesn't mean it will always use it for a window.

It depends on issues like X server resources at the time the window is created.

So I think that rdesktop should always (the default) use its own backing store and that the -B option is redundant and the internal variable g_ownbackstore should never be False because you don't know if the X server is actually going to use backing store for the window.