*** ./qtbase/src/plugins/platforms/cocoa/qnsview.mm
--- ./qtbase/src/plugins/platforms/cocoa/qnsview.mm
*************** static NSString *_q_NSWindowDidChangeOcc
*** 77,82 ****
--- 77,85 ----
  
  static bool _q_dontOverrideCtrlLMB = false;
  
+ // ### Mach port for the event tap to fix up the buttonNumber for Tablet right button mouse Events. (QTBUG-57487)
+ static CFMachPortRef _q_TableEventTapMachPort = 0;
+ 
  @interface NSEvent (Qt_Compile_Leopard_DeviceDelta)
    - (CGFloat)deviceDeltaX;
    - (CGFloat)deviceDeltaY;
*************** static bool _q_dontOverrideCtrlLMB = fal
*** 132,137 ****
--- 135,170 ----
  
  @implementation QT_MANGLE_NAMESPACE(QNSView)
  
+ // Event tap to fix up the right mouse buttonNumber to [theEvent buttonNumber] references below will work correctly
+ // for "right" button tablet events returned by some tablets. (QTBUG-57487)
+ static CGEventRef qnsTabletEventTap(CGEventTapProxy /*proxy*/, CGEventType type, CGEventRef inEvent, void *refCon)
+ {
+     Q_UNUSED(refCon);
+     switch (type)
+     {
+         case kCGEventRightMouseDown:
+         case kCGEventRightMouseUp:
+         case kCGEventRightMouseDragged:
+         {
+             int64_t subType = CGEventGetIntegerValueField(inEvent, kCGMouseEventSubtype);
+             if (subType == kCGEventMouseSubtypeTabletPoint)
+             {
+                 int64_t buttonNumber = CGEventGetIntegerValueField(inEvent, kCGMouseEventButtonNumber);
+                 if (buttonNumber != kCGMouseButtonRight)
+                 {
+                     CGEventSetIntegerValueField(inEvent, kCGMouseEventButtonNumber, kCGMouseButtonRight);
+                 }
+             }
+             break;
+         }
+ 
+         default:
+             break;
+     }
+ 
+     return inEvent;
+ }
+ 
  + (void)initialize
  {
      NSString **notificationNameVar = (NSString **)dlsym(RTLD_NEXT, "NSWindowDidChangeOcclusionStateNotification");
*************** static bool _q_dontOverrideCtrlLMB = fal
*** 139,144 ****
--- 172,197 ----
          _q_NSWindowDidChangeOcclusionStateNotification = *notificationNameVar;
  
      _q_dontOverrideCtrlLMB = qt_mac_resolveOption(false, "QT_MAC_DONT_OVERRIDE_CTRL_LMB");
+ 
+     // Use event tap to fix up the incorrect [NSEvent buttonNumber] returned for "right" button tablet events
+     // returned by some tablets. (QTBUG-57487)
+     static bool useTabletEventTap = qt_mac_resolveOption(true, "QT_MAC_USE_TABLET_EVENTTAP");
+     if (!_q_TableEventTapMachPort && useTabletEventTap)
+     {
+         pid_t pid = getpid();
+         ProcessSerialNumber psn;
+         GetProcessForPID(pid, &psn);
+ 
+         CGEventMask eventMask = CGEventMaskBit(kCGEventRightMouseDown)
+                               | CGEventMaskBit(kCGEventRightMouseUp)
+                               | CGEventMaskBit(kCGEventRightMouseDragged);
+ 
+         _q_TableEventTapMachPort = CGEventTapCreateForPSN(&psn, kCGHeadInsertEventTap, kCGEventTapOptionDefault, eventMask,
+                                                           qnsTabletEventTap, NULL);
+ 
+         CFRunLoopSourceRef eventSrc = CFMachPortCreateRunLoopSource(NULL, _q_TableEventTapMachPort, 0);
+         CFRunLoopAddSource((CFRunLoopRef) GetCFRunLoopFromEventLoop(GetMainEventLoop()), eventSrc, kCFRunLoopCommonModes);
+     }
  }
  
  - (id) init
*************** Q_GLOBAL_STATIC(QCocoaTabletDeviceDataHa
*** 1200,1206 ****
      NSPoint tilt = [theEvent tilt];
      int xTilt = qRound(tilt.x * 60.0);
      int yTilt = qRound(tilt.y * -60.0);
!     Qt::MouseButtons buttons = static_cast<Qt::MouseButtons>(static_cast<uint>([theEvent buttonMask]));
      qreal tangentialPressure = 0;
      qreal rotation = 0;
      int z = 0;
--- 1253,1267 ----
      NSPoint tilt = [theEvent tilt];
      int xTilt = qRound(tilt.x * 60.0);
      int yTilt = qRound(tilt.y * -60.0);
!     // If we are using the event tab then m_buttons will have the valid button state even for right clicks. (QTBUG-57487)
!     // Please note that the older code is incorrect because it maps the physical tablet buttons: NSPenTipMask, NSPenLowerSideMask,
!     // NSPenUpperSideMask. We are leaving this old code path here so we can test both code paths a runtime for acceptance
!     // testing. Once that changes have been verified by QA we will remove the old code.
!     Qt::MouseButtons buttons;
!     if (_q_TableEventTapMachPort)
!         buttons = m_buttons;
!     else
!         buttons = static_cast<Qt::MouseButtons>(static_cast<uint>([theEvent buttonMask]));
      qreal tangentialPressure = 0;
      qreal rotation = 0;
      int z = 0;