Make button numbers consistent across platforms

There's no universal consensus on how buttons are numbered.  Left, right,
middle as 0, 1, 2 seems to be the most common convention on modern vaguely
similar libraries, so I've gone with that.

The switch to zero-based indices will obviously break all current client code.
Particularly since now is the time to finish any breaking changes before a
stable release, I think that is better than only changing the middle and right
numbers, which would likely go unnoticed.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/mac.m b/src/mac.m
index 5a10964..84530b4 100644
--- a/src/mac.m
+++ b/src/mac.m
@@ -448,7 +448,7 @@ handleCrossing(PuglWrapperView* view, NSEvent* event, const PuglEventType type)
     rloc.x,
     [[NSScreen mainScreen] frame].size.height - rloc.y,
     getModifiers(event),
-    (uint32_t)[event buttonNumber] + 1,
+    (uint32_t)[event buttonNumber],
   };
 
   PuglEvent pressEvent;
@@ -469,7 +469,7 @@ handleCrossing(PuglWrapperView* view, NSEvent* event, const PuglEventType type)
     rloc.x,
     [[NSScreen mainScreen] frame].size.height - rloc.y,
     getModifiers(event),
-    (uint32_t)[event buttonNumber] + 1,
+    (uint32_t)[event buttonNumber],
   };
 
   PuglEvent releaseEvent;