Thanks to Björn Hein for spotting mistakes in EventQueue.cpp and StateSetManipulator, now fixed by Robert Osfield. Problems were:

"StateSetManipulator.cpp (rev 1.12, l. 85): cyclePolygonMode() is called but
no aa.requestRedraw() afterwards. Is this intended?

EventQueue.cpp (rev 1.8): in keyRelease & keyPressed KEY_Alt_R was mapped to
MODKEY_LEFT_ALT"

src/osgGA/StateSetManipulator.cpp

@@ -83,6 +83,7 @@ bool StateSetManipulator::handle(const GUIEventAdapter& ea,GUIActionAdapter& aa)
 
             case 'w' :
                 cyclePolygonMode();
+                aa.requestRedraw();
                 break;
 
 #if COMPILE_TEXENVFILTER_USAGE
@@ -97,6 +98,7 @@ bool StateSetManipulator::handle(const GUIEventAdapter& ea,GUIActionAdapter& aa)
 
                     // cycle through the available modes.
                     texenvfilter->setLodBias(texenvfilter->getLodBias()+0.1);
+                    aa.requestRedraw();
                 }
                 break;
 #endif