Merge pull request #632 from nithins/for-upstream

ngui refresh fix

Former-commit-id: 5052ea70a58642f41e85384a5cbfd1455d236f5b

include/igl/viewer/Viewer.cpp

@@ -793,6 +793,7 @@ namespace viewer
         break;
 
 #ifdef IGL_VIEWER_WITH_NANOGUI
+	ngui->refresh();
 	screen->drawContents();
 	screen->drawWidgets();
 #endif