Dedupe handling of mouse buttons in macos backend.

AFAICT `mouseDown()` and friends already check `[event type]` and
correctly handle right/middle button events, so the other event handlers
can just defer to them.

The point of the deduplication is so that future event rearchitecting
doesn't have to repeat loads of keyboard-modifiers handling code in each
of these handlers.

Author: anntzer

src/_macosx.m

@@ -1885,127 +1885,12 @@ - (void)mouseDragged:(NSEvent *)event
     PyGILState_Release(gstate);
 }
 
-- (void)rightMouseDown:(NSEvent *)event
-{
-    int x, y;
-    int num = 3;
-    int dblclick = 0;
-    PyObject* result;
-    PyGILState_STATE gstate;
-    NSPoint location = [event locationInWindow];
-    location = [self convertPoint: location fromView: nil];
-    x = location.x * device_scale;
-    y = location.y * device_scale;
-    gstate = PyGILState_Ensure();
-    if ([event clickCount] == 2) {
-      dblclick = 1;
-    }
-    result = PyObject_CallMethod(canvas, "button_press_event", "iiii", x, y, num, dblclick);
-    if(result)
-        Py_DECREF(result);
-    else
-        PyErr_Print();
-
-    PyGILState_Release(gstate);
-}
-
-- (void)rightMouseUp:(NSEvent *)event
-{
-    int x, y;
-    int num = 3;
-    PyObject* result;
-    PyGILState_STATE gstate;
-    NSPoint location = [event locationInWindow];
-    location = [self convertPoint: location fromView: nil];
-    x = location.x * device_scale;
-    y = location.y * device_scale;
-    gstate = PyGILState_Ensure();
-    result = PyObject_CallMethod(canvas, "button_release_event", "iii", x, y, num);
-    if(result)
-        Py_DECREF(result);
-    else
-        PyErr_Print();
-
-    PyGILState_Release(gstate);
-}
-
-- (void)rightMouseDragged:(NSEvent *)event
-{
-    int x, y;
-    NSPoint location = [event locationInWindow];
-    location = [self convertPoint: location fromView: nil];
-    x = location.x * device_scale;
-    y = location.y * device_scale;
-    PyGILState_STATE gstate = PyGILState_Ensure();
-    PyObject* result = PyObject_CallMethod(canvas, "motion_notify_event", "ii", x, y);
-    if(result)
-        Py_DECREF(result);
-    else
-        PyErr_Print();
-
-    PyGILState_Release(gstate);
-}
-
-- (void)otherMouseDown:(NSEvent *)event
-{
-    int x, y;
-    int num = 2;
-    int dblclick = 0;
-    PyObject* result;
-    PyGILState_STATE gstate;
-    NSPoint location = [event locationInWindow];
-    location = [self convertPoint: location fromView: nil];
-    x = location.x * device_scale;
-    y = location.y * device_scale;
-    gstate = PyGILState_Ensure();
-    if ([event clickCount] == 2) {
-      dblclick = 1;
-    }
-    result = PyObject_CallMethod(canvas, "button_press_event", "iiii", x, y, num, dblclick);
-    if(result)
-        Py_DECREF(result);
-    else
-        PyErr_Print();
-
-    PyGILState_Release(gstate);
-}
-
-- (void)otherMouseUp:(NSEvent *)event
-{
-    int x, y;
-    int num = 2;
-    PyObject* result;
-    PyGILState_STATE gstate;
-    NSPoint location = [event locationInWindow];
-    location = [self convertPoint: location fromView: nil];
-    x = location.x * device_scale;
-    y = location.y * device_scale;
-    gstate = PyGILState_Ensure();
-    result = PyObject_CallMethod(canvas, "button_release_event", "iii", x, y, num);
-    if(result)
-        Py_DECREF(result);
-    else
-        PyErr_Print();
-
-    PyGILState_Release(gstate);
-}
-
-- (void)otherMouseDragged:(NSEvent *)event
-{
-    int x, y;
-    NSPoint location = [event locationInWindow];
-    location = [self convertPoint: location fromView: nil];
-    x = location.x * device_scale;
-    y = location.y * device_scale;
-    PyGILState_STATE gstate = PyGILState_Ensure();
-    PyObject* result = PyObject_CallMethod(canvas, "motion_notify_event", "ii", x, y);
-    if(result)
-        Py_DECREF(result);
-    else
-        PyErr_Print();
-
-    PyGILState_Release(gstate);
-}
+- (void)rightMouseDown:(NSEvent *)event { [self mouseDown: event]; }
+- (void)rightMouseUp:(NSEvent *)event { [self mouseUp: event]; }
+- (void)rightMouseDragged:(NSEvent *)event { [self mouseDragged: event]; }
+- (void)otherMouseDown:(NSEvent *)event { [self mouseDown: event]; }
+- (void)otherMouseUp:(NSEvent *)event { [self mouseUp: event]; }
+- (void)otherMouseDragged:(NSEvent *)event { [self mouseDragged: event]; }
 
 - (void)setRubberband:(NSRect)rect
 {