back/x11: report AppKit button numbers from -[NSEvent buttonNumber] (#160)

-[NSEvent buttonNumber] is documented to number the left button 0, the right
button 1 and the middle button 2.  The X11 backend passed the X11 button
number straight through, so it reported the left button as 1, the right
button as 3, and only the middle button (2) matched by coincidence.

Set the button number from the AppKit event type when building the mouse
event for a button press, release or drag.  The X11 numbering in
generic.lMouse and friends is still used to match the incoming X event.

Author: DTW-Thalion

Source/x11/XGServerEvent.m

@@ -466,17 +466,20 @@ - (void) processEvent: (XEvent *) event
 	deltaX = 0.0;
         deltaY = 0.0;
 
+        /* -[NSEvent buttonNumber] uses the AppKit numbering, where the left
+         * button is 0, the right button is 1 and the middle button is 2,
+         * unlike the X11 numbering held in generic.lMouse and friends. */
         if (xEvent.xbutton.button == generic.lMouse)
           {
             if (swapMouseButtons)
               {
                 eventType = NSRightMouseDown;
-                buttonNumber = generic.rMouse;
+                buttonNumber = 1;
               }
             else
               {
                 eventType = NSLeftMouseDown;
-                buttonNumber = generic.lMouse;
+                buttonNumber = 0;
               }
           }
         else if (xEvent.xbutton.button == generic.rMouse
@@ -485,19 +488,19 @@ - (void) processEvent: (XEvent *) event
             if (swapMouseButtons)
               {
                 eventType = NSLeftMouseDown;
-                buttonNumber = generic.lMouse;
+                buttonNumber = 0;
               }
             else
               {
                 eventType = NSRightMouseDown;
-                buttonNumber = generic.rMouse;
+                buttonNumber = 1;
               }
           }
         else if (xEvent.xbutton.button == generic.mMouse
                  && generic.mMouse != 0)
           {
             eventType = NSOtherMouseDown;
-            buttonNumber = generic.mMouse;
+            buttonNumber = 2;
           }
         else if (xEvent.xbutton.button == generic.upMouse
                  && generic.upMouse != 0)
@@ -579,7 +582,7 @@ - (void) processEvent: (XEvent *) event
                      eventNumber: xEvent.xbutton.serial
                      clickCount: clickCount
                      pressure: 1.0
-                     buttonNumber: buttonNumber /* FIXME */
+                     buttonNumber: buttonNumber
                      deltaX: deltaX
                      deltaY: deltaY
                      deltaZ: 0.];
@@ -594,12 +597,12 @@ - (void) processEvent: (XEvent *) event
             if (swapMouseButtons)
               {
                 eventType = NSRightMouseUp;
-                buttonNumber = generic.rMouse;
+                buttonNumber = 1;
               }
             else
               {
                 eventType = NSLeftMouseUp;
-                buttonNumber = generic.lMouse;
+                buttonNumber = 0;
               }
           }
         else if (xEvent.xbutton.button == generic.rMouse
@@ -608,19 +611,19 @@ - (void) processEvent: (XEvent *) event
             if (swapMouseButtons)
               {
                 eventType = NSLeftMouseUp;
-                buttonNumber = generic.lMouse;
+                buttonNumber = 0;
               }
             else
               {
                 eventType = NSRightMouseUp;
-                buttonNumber = generic.rMouse;
+                buttonNumber = 1;
               }
           }
         else if (xEvent.xbutton.button == generic.mMouse
                  && generic.mMouse != 0)
           {
             eventType = NSOtherMouseUp;
-            buttonNumber = generic.mMouse;
+            buttonNumber = 2;
           }
         else
           {
@@ -652,7 +655,7 @@ - (void) processEvent: (XEvent *) event
                      eventNumber: xEvent.xbutton.serial
                      clickCount: clickCount
                      pressure: 1.0
-                     buttonNumber: buttonNumber        /* FIXMME */
+                     buttonNumber: buttonNumber
                      deltaX: 0.0
                      deltaY: 0.0
                      deltaZ: 0.0];
@@ -1539,18 +1542,22 @@ - (void) processEvent: (XEvent *) event
           if (state & generic.lMouseMask)
             {
               eventType = NSLeftMouseDragged;
+              buttonNumber = 0;
             }
           else if (state & generic.rMouseMask)
             {
               eventType = NSRightMouseDragged;
+              buttonNumber = 1;
             }
           else if (state & generic.mMouseMask)
             {
               eventType = NSOtherMouseDragged;
+              buttonNumber = 2;
             }
           else
             {
               eventType = NSMouseMoved;
+              buttonNumber = 0;
             }
 
           eventFlags = process_modifier_flags(state);
@@ -1579,7 +1586,7 @@ - (void) processEvent: (XEvent *) event
                        eventNumber: xEvent.xbutton.serial
                        clickCount: clickCount
                        pressure: 1.0
-                       buttonNumber: 0 /* FIXME */
+                       buttonNumber: buttonNumber
                        deltaX: deltaX
                        deltaY: deltaY
                        deltaZ: 0];