private void CloneCommon(Freezable sourceFreezable)
{
D3DImage source = (D3DImage)sourceFreezable;
_dpiX = source._dpiX;
_dpiY = source._dpiY;
Lock();
// If we've lost the front buffer, _pUserSurface unsafe will be null
SetBackBuffer(D3DResourceType.IDirect3DSurface9, source._pUserSurfaceUnsafe);
Unlock();
}