src/java.desktop/unix/classes/sun/awt/X11/XWindow.java

@@ -570,10 +570,18 @@
             postEventToEventQueue(event);
         }
     }
 
     static int getModifiers(int state, int button, int keyCode) {
+        return getModifiers(state, button, keyCode, false);
+    }
+
+    static int getWheelModifiers(int state, int button) {
+        return getModifiers(state, button, 0, true);
+    }
+
+    private static int getModifiers(int state, int button, int keyCode, boolean isWheelMouse) {
         int modifiers = 0;
 
         if (((state & XConstants.ShiftMask) != 0) ^ (keyCode == KeyEvent.VK_SHIFT)) {
             modifiers |= InputEvent.SHIFT_DOWN_MASK;
         }

@@ -600,11 +608,11 @@
             // 1) current button is now still in PRESSED state (means that user just pressed mouse but not released yet) or
             // 2) if Xsystem reports that "state" represents that button was just released. This only happens on RELEASE with 1,2,3 buttons.
             // ONLY one of these conditions should be TRUE to add that modifier.
             if (((state & XlibUtil.getButtonMask(i + 1)) != 0) != (button == XConstants.buttons[i])){
                 //exclude wheel buttons from adding their numbers as modifiers
-                if (!isWheel(XConstants.buttons[i])) {
+                if (!isWheelMouse || !isWheel(XConstants.buttons[i])) {
                     modifiers |= InputEvent.getMaskForButton(i+1);
                 }
             }
         }
         return modifiers;

@@ -713,13 +721,13 @@
         }
 
         if (button > XConstants.buttons[4]){
             button -= 2;
         }
-        modifiers = getModifiers(xbe.get_state(),button,0);
 
         if (!isWheel(lbutton)) {
+            modifiers = getModifiers(xbe.get_state(), button, 0);
             MouseEvent me = new MouseEvent(getEventSource(),
                                            type == XConstants.ButtonPress ? MouseEvent.MOUSE_PRESSED : MouseEvent.MOUSE_RELEASED,
                                            jWhen,modifiers, x, y,
                                            xbe.get_x_root(),
                                            xbe.get_y_root(),

@@ -741,10 +749,11 @@
                                                      false, button));
             }
 
         }
         else {
+            modifiers = getWheelModifiers(xbe.get_state(), button);
             if (xev.get_type() == XConstants.ButtonPress) {
                 MouseWheelEvent mwe = new MouseWheelEvent(getEventSource(),MouseEvent.MOUSE_WHEEL, jWhen,
                                                           modifiers,
                                                           x, y,
                                                           xbe.get_x_root(),