* lisp/xt-mouse.el (xterm-mouse--read-event-sequence-1000):

Always store button numbers in the same way in xterm-mouse-last;
Don't burp is xterm-mouse-last is not set as expected.
Never return negative indices.

Fixes: debbugs:17378

2 files changed, 11 insertions, 4 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 7c838a61fe5..043a0c240b1 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,10 @@
+2014-05-05  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+        * xt-mouse.el (xterm-mouse--read-event-sequence-1000): (bug#17378)
+        Always store button numbers in the same way in xterm-mouse-last;
+        Don't burp is xterm-mouse-last is not set as expected.
+        Never return negative indices.
+
 2014-05-05  Dmitry Gutov  <dgutov@yandex.ru>
 
         * progmodes/ruby-mode.el (ruby-syntax-propertize-function):
diff --git a/lisp/xt-mouse.el b/lisp/xt-mouse.el
index 26a07b46840..87e65f7e117 100644
--- a/lisp/xt-mouse.el
+++ b/lisp/xt-mouse.el
@@ -161,10 +161,10 @@ http://invisible-island.net/xterm/ctlseqs/ctlseqs.html)."
            (cond ((>= code 64)
                   (format "mouse-%d" (- code 60)))
                  ((memq code '(8 9 10))
-                  (setq xterm-mouse-last code)
+                  (setq xterm-mouse-last (- code 8))
                   (format "M-down-mouse-%d" (- code 7)))
                  ((= code 11)
-                  (format "M-mouse-%d" (- xterm-mouse-last 7)))
+                  (format "M-mouse-%d" (+ 1 (or xterm-mouse-last 0))))
                  ((= code 3)
                   ;; For buttons > 5 xterm only reports a
                   ;; button-release event.  Avoid error by mapping
@@ -174,8 +174,8 @@ http://invisible-island.net/xterm/ctlseqs/ctlseqs.html)."
                   (setq xterm-mouse-last code)
                   (format "down-mouse-%d" (+ 1 code))))))
         ;; x and y coordinates
-        (- (read-event) 33)
-        (- (read-event) 33)))
+        (max 0 (- (read-event) 33))
+        (max 0 (- (read-event) 33))))
 
 ;; XTerm's 1006-mode terminal mouse click reporting has the form
 ;; <BUTTON> ; <X> ; <Y> <M or m>, where the button and ordinates are