Push current position to navqueue before navigating back (#1537)

src/navqueue.c

@@ -192,6 +192,20 @@ static gboolean goto_file_pos(const gchar *file, gint pos)
 void navqueue_go_back(void)
 {
 	filepos *fprev;
+	GeanyDocument *doc = document_get_current();
+
+	/* If the navqueue is currently at some position A, but the actual cursor is at some other
+	 * place B, we should add B to the navqueue, so that (1) we go back to A, not to the next
+	 * item in the queue; and (2) we can later restore B by going forward.
+	 * (If A = B, add_new_position will ignore it.) */
+	if (doc)
+	{
+		if (doc->file_name)
+			add_new_position(doc->file_name, sci_get_current_position(doc->editor->sci));
+	}
+	else
+		/* see also https://github.com/geany/geany/pull/1537 */
+		g_warning("Attempted navigation when nothing is open");
 
 	/* return if theres no place to go back to */
 	if (g_queue_is_empty(navigation_queue) ||