Handle mouse leaving initial window in `mouse-set-region' (Bug#23707)

* lisp/mouse.el (mouse-set-region): If the mouse ends up in
another window or on the menu bar, use `window-point' of
selected window instead of `posn-point' of the event end
(Bug#23707).

1 files changed, 6 insertions, 1 deletions

diff --git a/lisp/mouse.el b/lisp/mouse.el
index 592338ad09d..64ee796a681 100644
--- a/lisp/mouse.el
+++ b/lisp/mouse.el
@@ -566,7 +566,12 @@ command alters the kill ring or not."
   (mouse-minibuffer-check click)
   (select-window (posn-window (event-start click)))
   (let ((beg (posn-point (event-start click)))
-        (end (posn-point (event-end click)))
+        (end
+         (if (eq (posn-window (event-end click)) (selected-window))
+             (posn-point (event-end click))
+           ;; If the mouse ends up in any other window or on the menu
+           ;; bar, use `window-point' of selected window (Bug#23707).
+           (window-point)))
         (click-count (event-click-count click)))
     (let ((drag-start (terminal-parameter nil 'mouse-drag-start)))
       (when drag-start