From c0a0ddf1e026c0a67f517839b8ca658b1345cf58 Mon Sep 17 00:00:00 2001
From: wmayer <wmayer@users.sourceforge.net>
Date: Fri, 24 Mar 2023 19:52:15 +0100
Subject: [PATCH] Gui: by default restore the last visited page in the
 preferences dialog

See also: https://forum.freecad.org/viewtopic.php?t=77071
---
 src/Gui/CommandStd.cpp        | 13 ++++++++++++-
 src/Gui/DlgPreferencesImp.cpp | 23 ++++++++++++++++++++---
 src/Gui/DlgPreferencesImp.h   |  3 ++-
 3 files changed, 34 insertions(+), 5 deletions(-)

diff --git a/src/Gui/CommandStd.cpp b/src/Gui/CommandStd.cpp
index cdfd61c2ff..4141b754fd 100644
--- a/src/Gui/CommandStd.cpp
+++ b/src/Gui/CommandStd.cpp
@@ -370,8 +370,19 @@ Action * StdCmdDlgPreferences::createAction()
 void StdCmdDlgPreferences::activated(int iMsg)
 {
     Q_UNUSED(iMsg);
+
+    static QString groupName{};
+    static int index{};
+
     Gui::Dialog::DlgPreferencesImp cDlg(getMainWindow());
-    cDlg.exec();
+    ParameterGrp::handle hGrp = App::GetApplication().GetParameterGroupByPath("User parameter:BaseApp/Preferences");
+    if (hGrp->GetBool("RestoreGroupPage", true)) {
+        cDlg.activateGroupPage(groupName, index);
+    }
+
+    if (cDlg.exec()) {
+        cDlg.activeGroupPage(groupName, index);
+    }
 }
 
 //===========================================================================
diff --git a/src/Gui/DlgPreferencesImp.cpp b/src/Gui/DlgPreferencesImp.cpp
index cca16af18f..e2b98f5c60 100644
--- a/src/Gui/DlgPreferencesImp.cpp
+++ b/src/Gui/DlgPreferencesImp.cpp
@@ -305,13 +305,30 @@ void DlgPreferencesImp::activateGroupPage(const QString& group, int index)
         QListWidgetItem* item = ui->listBox->item(i);
         if (item->data(GroupNameRole).toString() == group) {
             ui->listBox->setCurrentItem(item);
-            auto tabWidget = static_cast<QTabWidget*>(ui->tabWidgetStack->widget(i));
-            tabWidget->setCurrentIndex(index);
-            break;
+            auto tabWidget = dynamic_cast<QTabWidget*>(ui->tabWidgetStack->widget(i));
+            if (tabWidget) {
+                tabWidget->setCurrentIndex(index);
+                break;
+            }
         }
     }
 }
 
+/**
+ * Returns the group name \a group and position \a index of the active page.
+ */
+void DlgPreferencesImp::activeGroupPage(QString& group, int& index) const
+{
+    int row = ui->listBox->currentRow();
+    auto item = ui->listBox->item(row);
+    auto tabWidget = dynamic_cast<QTabWidget*>(ui->tabWidgetStack->widget(row));
+
+    if (item && tabWidget) {
+        group = item->data(GroupNameRole).toString();
+        index = tabWidget->currentIndex();
+    }
+}
+
 void DlgPreferencesImp::accept()
 {
     this->invalidParameter = false;
diff --git a/src/Gui/DlgPreferencesImp.h b/src/Gui/DlgPreferencesImp.h
index 762c9a6737..2c5de5d002 100644
--- a/src/Gui/DlgPreferencesImp.h
+++ b/src/Gui/DlgPreferencesImp.h
@@ -123,7 +123,8 @@ public:
 
     void accept() override;
     void reload();
-    void activateGroupPage(const QString& group, int id);
+    void activateGroupPage(const QString& group, int index);
+    void activeGroupPage(QString& group, int& index) const;
 
 protected:
     void changeEvent(QEvent *e) override;