implement handling of GLDebugSwitch: we use glutReportErrors to check for errors in each iteration of the glut mainloop if requested

git-svn-id: https://svn.code.sf.net/p/freeglut/code/trunk@1641 7f0cb862-5218-0410-a997-914c9d46530a

freeglut/freeglut/src/fg_main.c

@@ -465,6 +465,13 @@ void FGAPIENTRY glutMainLoopEvent( void )
     /* Perform work on the window (position, reshape, display, etc) */
     fghProcessWork( );
 
+    /* Check OpenGL error state if requested.
+     * Don't call if no more open windows (can happen if user closes window from
+     * title bar), would lead to infinite error loop in glutReportErrors
+     */
+    if (fgState.GLDebugSwitch && fgStructure.CurrentWindow)
+        glutReportErrors( );
+
     fgCloseWindows( );
 }