Switch to direct rendering before clearing the screen (OpenGL GAL).

common/gal/opengl/opengl_gal.cpp

@@ -672,6 +672,7 @@ void OPENGL_GAL::Flush()
 void OPENGL_GAL::ClearScreen( const COLOR4D& aColor )
 {
     // Clear screen
+    compositor.SetBuffer( OPENGL_COMPOSITOR::DIRECT_RENDERING );
     glClearColor( aColor.r, aColor.g, aColor.b, aColor.a );
     glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
 }