[gnc-plugin-page-register] when reversing reversed txn, offer jump

When reversing a transaction which is already reversed, offer a jump
to the reversal transaction.

gnucash/gnome/gnc-plugin-page-register.c

@@ -4072,13 +4072,6 @@ gnc_plugin_page_register_cmd_reverse_transaction (GtkAction* action,
     if (trans == NULL)
         return;
 
-    if (xaccTransGetReversedBy (trans))
-    {
-        gnc_error_dialog (GTK_WINDOW (window), "%s",
-                          _ ("A reversing entry has already been created for this transaction."));
-        return;
-    }
-
     split = gnc_split_register_get_current_split (reg);
     account = xaccSplitGetAccount (split);
 
@@ -4088,6 +4081,17 @@ gnc_plugin_page_register_cmd_reverse_transaction (GtkAction* action,
         return;
     }
 
+    new_trans = xaccTransGetReversedBy (trans);
+    if (new_trans)
+    {
+        const char *rev = _("A reversing entry has already been created for this transaction.");
+        const char *jump = _("Jump to the transaction?");
+        if (gnc_verify_dialog (GTK_WINDOW (window), TRUE, "%s\n\n%s", rev, jump))
+            goto jump_to_trans;
+        else
+            return;
+    }
+
     if (!gnc_dup_time64_dialog (window, _("Reverse Transaction"),
                                 _("New Transaction Information"), &date))
     {
@@ -4104,6 +4108,7 @@ gnc_plugin_page_register_cmd_reverse_transaction (GtkAction* action,
 
     gnc_resume_gui_refresh();
 
+ jump_to_trans:
     /* Now jump to new trans */
     gsr = gnc_plugin_page_register_get_gsr (GNC_PLUGIN_PAGE (page));
     split = xaccTransFindSplitByAccount(new_trans, account);