Add initial prototype.

3-mid/opengl/source/desk/opengl-raster.adb

@@ -0,0 +1,13 @@
+package body openGL.Raster
+is
+
+   procedure set_Window_Position (X, Y : in Real;
+                                  Z    : in Real := 0.0;
+                                  W    : in Real := 1.0)
+   is
+      pragma Unreferenced (Z, W);
+   begin
+      raise Program_Error with "TODO: unimplemented";
+   end set_Window_Position;
+
+end openGL.Raster;