diff -up freeglut-2.8.0/src/freeglut_xinput.c.btnmask freeglut-2.8.0/src/freeglut_xinput.c
--- freeglut-2.8.0/src/freeglut_xinput.c.btnmask	2012-08-27 15:55:07.841482330 +0200
+++ freeglut-2.8.0/src/freeglut_xinput.c	2012-08-27 15:57:12.423604612 +0200
@@ -13,6 +13,9 @@
 #include <X11/Xlib.h>
 #include <X11/extensions/XInput2.h>
 
+/* convert the XInput button state mask to the regular X mouse event button mask */
+#define BUTTON_MASK(xistate)    ((xistate) << 8)
+
 /* import function from freeglut_main.c */
 int fghGetXModifiers( int state );
 
@@ -188,7 +191,7 @@ void fgHandleExtensionEvents( XEvent* ba
 			std_ev.xcrossing.detail = evcross->detail;
 			std_ev.xcrossing.same_screen = evcross->same_screen;
 			std_ev.xcrossing.focus = evcross->focus;
-			std_ev.xcrossing.state = *(unsigned int*)evcross->buttons.mask;
+			std_ev.xcrossing.state = BUTTON_MASK(*(unsigned int*)evcross->buttons.mask);
 
 			XPutBackEvent(fgDisplay.Display, &std_ev);
 			break;
@@ -213,7 +216,7 @@ void fgHandleExtensionEvents( XEvent* ba
 			std_ev.xbutton.y = event->event_y;
 			std_ev.xbutton.x_root = event->root_x;
 			std_ev.xbutton.y_root = event->root_y;
-			std_ev.xbutton.state = *(unsigned int*)event->buttons.mask;
+			std_ev.xbutton.state = BUTTON_MASK(*(unsigned int*)event->buttons.mask);
 			std_ev.xbutton.button = event->detail;
 
 			XPutBackEvent(fgDisplay.Display, &std_ev);
@@ -245,7 +248,7 @@ void fgHandleExtensionEvents( XEvent* ba
 			std_ev.xmotion.y = event->event_y;
 			std_ev.xmotion.x_root = event->root_x;
 			std_ev.xmotion.y_root = event->root_y;
-			std_ev.xmotion.state = *(unsigned int*)event->buttons.mask;
+			std_ev.xmotion.state = BUTTON_MASK(*(unsigned int*)event->buttons.mask);
 			std_ev.xmotion.is_hint = NotifyNormal;
 
 			XPutBackEvent(fgDisplay.Display, &std_ev);