better fix than commit c0bc2f1 that tried to fix an overzealous event propagation:

The fix is now only for Windows, because it creates issues and does not fix the special keys issues on Linux.
This is due to the serious differences in event management between platforms.

common/tool/tool_dispatcher.cpp

@@ -323,10 +323,31 @@ void TOOL_DISPATCHER::DispatchWxEvent( wxEvent& aEvent )
 
     if( evt )
         m_toolMgr->ProcessEvent( *evt );
-    else
-        // pass the event to the GUI, it might still be interested in it
+
+    // pass the event to the GUI, it might still be interested in it
+#ifdef __APPLE__
+    // On OS X, key events are always meant to be caught.  An uncaught key event is assumed
+    // to be a user input error by OS X (as they are pressing keys in a context where nothing
+    // is there to catch the event).  This annoyingly makes OS X beep and/or flash the screen
+    // in pcbnew and the footprint editor any time a hotkey is used.  The correct procedure is
+    // to NOT pass key events to the GUI under OS X.
+
+    if( type != wxEVT_CHAR )
         aEvent.Skip();
 
+#elif defined ( __WINDOWS__ )
+    // On Windows, mouse wheel event and some keys event (PAGE UP, PAGE DOWN, ARROW KEYS) are previoulsy
+    // called, and calling aEvent.Skip() calls default handler for these specific keys equivalent to move
+    // the thumbtrack cursor.
+    // TODO: see a better filtering could be just mouse wheel and these special keys only.
+
+    if( !evt )
+        aEvent.Skip();
+#else
+    // on Linux, the event must be passed to the GUI
+    aEvent.Skip();
+#endif
+
     updateUI();
 }