hdevpal (ULONG) - input
If hdevpal=0, ppalinfo points to a palette information structure, which must be set into a new palette. The handle for this new palette is returned in hdevpal. The new palette is then selected into the DC.
If hdevpal is nonzero, ppalinfo is ignored, the palette is selected into the DC, and hdevpal is a device palette handle previously returned by the presentation driver. In this case, hdevpal is used to bind the palette with the new DC. This technique is the driver-level mechanism for sharing palettes among contexts on the same device.