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, 8 insertions, 1 deletions

diff --git a/src/x11.c b/src/x11.c
index 614b7ac..ed249a8 100644
--- a/src/x11.c
+++ b/src/x11.c
@@ -741,7 +741,14 @@ translateEvent(PuglView* const view, XEvent xevent)
       event.button.xRoot  = xevent.xbutton.x_root;
       event.button.yRoot  = xevent.xbutton.y_root;
       event.button.state  = translateModifiers(xevent.xbutton.state);
-      event.button.button = xevent.xbutton.button;
+      event.button.button = xevent.xbutton.button - 1;
+      if (event.button.button == 1) {
+        event.button.button = 2;
+      } else if (event.button.button == 2) {
+        event.button.button = 1;
+      } else if (event.button.button >= 7) {
+        event.button.button -= 4;
+      }
     }
     break;
   case KeyPress: