(minibuffer-window-active-p): New function.

1 files changed, 13 insertions, 0 deletions

diff --git a/lisp/subr.el b/lisp/subr.el
index c1717f553d3..e5f4189ebcb 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -83,6 +83,19 @@ If ALL-FRAMES is neither nil nor t, stick strictly to the selected frame."
              (funcall proc walk-windows-current)
              (not (eq walk-windows-current walk-windows-start))))))
 
+(defun minibuffer-window-active-p (window)
+  "Return t if WINDOW (a minibuffer window) is now active."
+  ;; nil nil means include WINDOW's frame
+  ;; and other frames using WINDOW as minibuffer,
+  ;; and include minibuffer if active.
+  (let ((prev (previous-window window nil nil)))
+    ;; If PREV equals WINDOW, WINDOW must be on a minibuffer-only frame
+    ;; and it's not currently being used.  So return nil.
+    (and (not (eq window prev))
+         (let ((should-be-same (next-window prev nil nil)))
+           ;; If next-window doesn't reverse previous-window,
+           ;; WINDOW must be outside the cycle specified by nil nil.
+           (eq should-be-same window)))))
 
 ;;;; Keymap support.