Support forward and back mouse button events

ChangeLog.md

@@ -93,6 +93,10 @@ if bump scrolling is enabled.  Setting the `turbovnc.fshidedock` system
 property to `0` or `1` causes the viewer to always show or always hide the menu
 bar and dock in full-screen mode, irrespective of bump scrolling.
 
+12. The TurboVNC Server and Viewer now implement the Extended Mouse Buttons
+RFB extension, which allows forward and back mouse button events to be
+transmitted to the VNC server.
+
 
 3.1.4
 =====

common/rfb/rfbproto.h

@@ -1,5 +1,5 @@
-/* Copyright (C) 2009-2010, 2012-2013, 2015, 2022, 2024 D. R. Commander.
- *                                                      All Rights Reserved.
+/* Copyright (C) 2009-2010, 2012-2013, 2015, 2022, 2024-2025
+ *           D. R. Commander.  All Rights Reserved.
  * Copyright (C) 2009 Vic Lee.  All Rights Reserved.
  * Copyright (C) 2004-2008 Sun Microsystems, Inc. All Rights Reserved.
  * Copyright (C) 2000-2006 Constantin Kaplinsky. All Rights Reserved.
@@ -507,6 +507,7 @@ typedef struct _rfbInteractionCapsMsg {
  *   0xFFFFFE00 .. 0xFFFFFE64 -- fine-grained quality level (0-100 scale)
  *         -512 .. -412
  *   0xFFFFFEC3               -- Tight encoding without zlib
+ *   0xFFFFFEC4               -- Extended mouse buttons
  *   0xFFFFFEC7 .. 0xFFFFFEC8 -- flow control extensions
  *         -313 .. -312
  *   0xFFFFFECC               -- extended desktop size
@@ -546,6 +547,8 @@ typedef struct _rfbInteractionCapsMsg {
 
 #define rfbEncodingTightWithoutZlib     0xFFFFFEC3  /* -317 */
 
+#define rfbEncodingExtendedMouseButtons 0xFFFFFEC4  /* -316 */
+
 #define rfbEncodingContinuousUpdates    0xFFFFFEC7  /* -313 */
 #define rfbEncodingFence                0xFFFFFEC8  /* -312 */
 

java/com/turbovnc/rfb/CMsgHandler.java

@@ -1,5 +1,5 @@
-/* Copyright (C) 2011-2012, 2015, 2018, 2022 D. R. Commander.
- *                                           All Rights Reserved.
+/* Copyright (C) 2011-2012, 2015, 2018, 2022, 2025 D. R. Commander.
+ *                                                 All Rights Reserved.
  * Copyright 2009-2011, 2019 Pierre Ossman for Cendio AB
  * Copyright (C) 2011 Brian P. Hinz
  * Copyright (C) 2002-2005 RealVNC Ltd.  All Rights Reserved.
@@ -115,6 +115,8 @@ public void endOfContinuousUpdates() {
   public abstract void enableQEMUExtKeyEvent();
   public abstract void setLEDState(int state);
 
+  public abstract void enableExtMouseButtons();
+
   public abstract void setCursor(int width, int height, Point hotspot,
                                  int[] data, byte[] mask);
   public abstract void serverInit();

java/com/turbovnc/rfb/CMsgReader.java

@@ -1,4 +1,5 @@
-/* Copyright (C) 2012, 2017-2018, 2022 D. R. Commander.  All Rights Reserved.
+/* Copyright (C) 2012, 2017-2018, 2022, 2025 D. R. Commander.
+ *                                           All Rights Reserved.
  * Copyright 2016, 2018-2019 Pierre Ossman for Cendio AB
  * Copyright (C) 2002-2005 RealVNC Ltd.  All Rights Reserved.
  *
@@ -346,6 +347,9 @@ public void readMsg(Params params) {
         case RFB.ENCODING_VMWARE_LED_STATE:
           readVMwareLEDState();
           break;
+        case RFB.ENCODING_EXTENDED_MOUSE_BUTTONS:
+          handler.enableExtMouseButtons();
+          break;
         default:
           readRect(new Rect(x, y, x + w, y + h), encoding);
           break;

java/com/turbovnc/rfb/CMsgWriter.java

@@ -1,4 +1,4 @@
-/* Copyright (C) 2012, 2015, 2017-2018, 2020-2024 D. R. Commander.
+/* Copyright (C) 2012, 2015, 2017-2018, 2020-2025 D. R. Commander.
  *                                                All Rights Reserved.
  * Copyright 2009-2011, 2017-2019 Pierre Ossman for Cendio AB
  * Copyright (C) 2011, 2015 Brian P. Hinz
@@ -339,10 +339,18 @@ public synchronized void writePointerEvent(Point pos, int buttonMask)
     if (p.x >= cp.width) p.x = cp.width - 1;
     if (p.y >= cp.height) p.y = cp.height - 1;
 
+    int extButtonMask = 0;
+    if (cp.supportsExtMouseButtons && (buttonMask & 0xFF80) != 0) {
+      extButtonMask = (buttonMask & 0xFF80) >> 7;
+      buttonMask = (buttonMask & 0x7F) | 0x80;
+    }
+
     startMsg(RFB.POINTER_EVENT);
     os.writeU8(buttonMask);
     os.writeU16(p.x);
     os.writeU16(p.y);
+    if (extButtonMask != 0)
+      os.writeU8(extButtonMask);
     endMsg();
   }
 
@@ -419,6 +427,7 @@ public synchronized void writeSetEncodings(int preferredEncoding,
       encodings[nEncodings++] = RFB.ENCODING_VMWARE_LED_STATE;
     }
     encodings[nEncodings++] = RFB.ENCODING_TIGHT_WITHOUT_ZLIB;
+    encodings[nEncodings++] = RFB.ENCODING_EXTENDED_MOUSE_BUTTONS;
 
     if (Decoder.supported(preferredEncoding)) {
       encodings[nEncodings++] = preferredEncoding;

java/com/turbovnc/rfb/ConnParams.java

@@ -1,5 +1,5 @@
-/* Copyright (C) 2011-2012, 2015, 2018, 2022, 2024 D. R. Commander.
- *                                                 All Rights Reserved.
+/* Copyright (C) 2011-2012, 2015, 2018, 2022, 2024-2025 D. R. Commander.
+ *                                                      All Rights Reserved.
  * Copyright 2019 Pierre Ossman for Cendio AB
  * Copyright (C) 2012 Brian P. Hinz
  * Copyright (C) 2002-2005 RealVNC Ltd.  All Rights Reserved.
@@ -148,6 +148,7 @@ public void setClipboardCaps(int flags, int[] lengths)
   public boolean supportsLastRect;
   public boolean supportsGII;
   public boolean supportsQEMUExtKeyEvent;
+  public boolean supportsExtMouseButtons;
   public int ledState = RFB.LED_UNKNOWN;
 
   public boolean supportsSetDesktopSize;

java/com/turbovnc/rfb/RFB.java

@@ -1,5 +1,5 @@
-/* Copyright (C) 2011-2012, 2015-2018, 2021-2022, 2024 D. R. Commander.
- *                                                     All Rights Reserved.
+/* Copyright (C) 2011-2012, 2015-2018, 2021-2022, 2024-2025
+ *           D. R. Commander.  All Rights Reserved.
  * Copyright 2009, 2011, 2019 Pierre Ossman for Cendio AB
  * Copyright (C) 2011-2012 Brian P. Hinz
  * Copyright (C) 2002-2005 RealVNC Ltd.  All Rights Reserved.
@@ -219,6 +219,8 @@ public static String encodingName(int num) {
 
   public static final int ENCODING_TIGHT_WITHOUT_ZLIB      = -317;
 
+  public static final int ENCODING_EXTENDED_MOUSE_BUTTONS  = -316;
+
   public static final int ENCODING_CONTINUOUS_UPDATES      = -313;
   public static final int ENCODING_FENCE                   = -312;
 
@@ -341,6 +343,8 @@ public static String encodingName(int num) {
   public static final int BUTTON5_MASK = 16;
   public static final int BUTTON6_MASK = 32;
   public static final int BUTTON7_MASK = 64;
+  public static final int BUTTON8_MASK = 128;
+  public static final int BUTTON9_MASK = 256;
 
   //***************************************************************************
   // GII

java/com/turbovnc/vncviewer/CConn.java

@@ -964,6 +964,11 @@ public void enableQEMUExtKeyEvent() {
     }
   }
 
+  public void enableExtMouseButtons() {
+    vlog.info("Enabling Extended Mouse Buttons");
+    cp.supportsExtMouseButtons = true;
+  }
+
   // Sync server's LED state with the client's
   public void pushLEDState()
   {
@@ -2820,6 +2825,8 @@ public void writePointerEvent(MouseEvent ev) {
     if (state() != RFBSTATE_NORMAL || shuttingDown || benchmark)
       return;
 
+    boolean debugButton = true;
+
     switch (ev.getID()) {
       case MouseEvent.MOUSE_PRESSED:
         switch (ev.getButton()) {
@@ -2832,15 +2839,39 @@ public void writePointerEvent(MouseEvent ev) {
           case 4:
             // X11 uses Buttons 6 and 7 for (respectively) left and right
             // scroll wheel events, but Java/X11 uses Buttons 4 and 5.
-            if (!Utils.isX11()) return;
-            buttonMask |= RFB.BUTTON6_MASK;  break;
+            if (Utils.isX11()) {
+              buttonMask |= RFB.BUTTON6_MASK;
+              debugButton = false;
+            // X11 uses Buttons 8 and 9 for (respectively) back and forward
+            // buttons, but Java/macOS and Java/Windows use Buttons 4 and 5.
+            } else if (cp.supportsExtMouseButtons)
+              buttonMask |= RFB.BUTTON8_MASK;
+            else return;
+            break;
           case 5:
-            if (!Utils.isX11()) return;
-            buttonMask |= RFB.BUTTON7_MASK;  break;
+            if (Utils.isX11()) {
+              buttonMask |= RFB.BUTTON7_MASK;
+              debugButton = false;
+            } else if (cp.supportsExtMouseButtons)
+              buttonMask |= RFB.BUTTON9_MASK;
+            else return;
+            break;
+          case 6:
+            // X11 uses Buttons 8 and 9 for (respectively) back and forward
+            // buttons, but Java/X11 uses Buttons 6 and 7.
+            if (Utils.isX11() && cp.supportsExtMouseButtons)
+              buttonMask |= RFB.BUTTON8_MASK;
+            else return;
+            break;
+          case 7:
+            if (Utils.isX11() && cp.supportsExtMouseButtons)
+              buttonMask |= RFB.BUTTON9_MASK;
+            else return;
+            break;
           default:
             return;
         }
-        if (ev.getButton() <= 3)
+        if (debugButton)
           vlog.debug("mouse PRESS, button " + ev.getButton() +
                      ", coords " + ev.getX() + "," + ev.getY());
         break;
@@ -2853,15 +2884,35 @@ public void writePointerEvent(MouseEvent ev) {
           case 3:
             buttonMask &= ~RFB.BUTTON3_MASK;  break;
           case 4:
-            if (!Utils.isX11()) return;
-            buttonMask &= ~RFB.BUTTON6_MASK;  break;
+            if (Utils.isX11()) {
+              buttonMask &= ~RFB.BUTTON6_MASK;
+              debugButton = false;
+            } else if (cp.supportsExtMouseButtons)
+              buttonMask &= ~RFB.BUTTON8_MASK;
+            else return;
+            break;
           case 5:
-            if (!Utils.isX11()) return;
-            buttonMask &= ~RFB.BUTTON7_MASK;  break;
+            if (Utils.isX11()) {
+              buttonMask &= ~RFB.BUTTON7_MASK;
+              debugButton = false;
+            } else if (cp.supportsExtMouseButtons)
+              buttonMask &= ~RFB.BUTTON9_MASK;
+            else return;
+            break;
+          case 6:
+            if (Utils.isX11() && cp.supportsExtMouseButtons)
+              buttonMask &= ~RFB.BUTTON8_MASK;
+            else return;
+            break;
+          case 7:
+            if (Utils.isX11() && cp.supportsExtMouseButtons)
+              buttonMask &= ~RFB.BUTTON9_MASK;
+            else return;
+            break;
           default:
             return;
         }
-        if (ev.getButton() <= 3)
+        if (debugButton)
           vlog.debug("mouse release, button " + ev.getButton() +
                      ", coords " + ev.getX() + "," + ev.getY());
         break;

unix/Xvnc/programs/Xserver/hw/vnc/kbdptr.c

@@ -4,8 +4,8 @@
  *
  */
 
-/* Copyright (C) 2014-2016, 2019, 2021-2022, 2024 D. R. Commander.
- *                                                All Rights Reserved.
+/* Copyright (C) 2014-2016, 2019, 2021-2022, 2024-2025 D. R. Commander.
+ *                                                     All Rights Reserved.
  * Copyright (C) 2013, 2017-2018 Pierre Ossman for Cendio AB.
  *                               All Rights Reserved.
  * Copyright (C) 2009 Red Hat, Inc.  All Rights Reserved.
@@ -526,7 +526,7 @@ void PtrAddEvent(int buttonMask, int x, int y)
     cursorPosY = y;
   }
 
-  for (i = 0; i < 7; i++) {
+  for (i = 0; i < 9; i++) {
     if ((buttonMask ^ oldButtonMask) & (1 << i)) {
       if (buttonMask & (1 << i)) {
         valuator_mask_set_range(&mask, 0, 0, NULL);

unix/Xvnc/programs/Xserver/hw/vnc/rfb.h

@@ -2,7 +2,7 @@
  * rfb.h - header file for RFB DDX implementation.
  */
 
-/* Copyright (C) 2010-2024 D. R. Commander.  All Rights Reserved.
+/* Copyright (C) 2010-2025 D. R. Commander.  All Rights Reserved.
  * Copyright (C) 2011, 2015 Pierre Ossman for Cendio AB.  All Rights Reserved.
  * Copyright (C) 2011 Joel Martin
  * Copyright (C) 2011 Gernot Tenchio
@@ -444,6 +444,8 @@ typedef struct rfbClientRec {
                                        extension */
   Bool enableTightWithoutZlib;      /* client supports Tight Encoding Without
                                        Zlib extension */
+  Bool enableExtMouseButtons;       /* client supports Extended Mouse Buttons
+                                       extension */
   Bool useRichCursorEncoding;       /* rfbEncodingRichCursor is preferred */
   Bool cursorWasChanged;            /* cursor shape update should be sent */
   Bool cursorWasMoved;              /* cursor position update should be sent */
@@ -493,6 +495,8 @@ typedef struct rfbClientRec {
   Bool pendingDesktopResize, pendingExtDesktopResize;
   int reason, result;
 
+  Bool pendingExtMouseButtonsRect;
+
   /* Server-side key mapping */
   Bool pendingQEMUExtKeyEventRect, pendingLEDState;
   unsigned int ledState;