Make a setter for defaultSave path in qbtsession and do some other optimizations to avoid potential pitfalls.

src/addnewtorrentdialog.cpp

@@ -596,7 +596,6 @@ void AddNewTorrentDialog::on_buttonBox_accepted()
   pref.useAdditionDialog(!ui->never_show_cb->isChecked());
   if (ui->default_save_path_cb->isChecked()) {
     pref.setSavePath(ui->save_path_combo->itemData(ui->save_path_combo->currentIndex()).toString());
-    pref.sync();
-    QBtSession::instance()->configureSession();
+    QBtSession::instance()->setDefaultSavePath(pref.getSavePath());
   }
 }

src/qtlibtorrent/qbtsession.cpp

@@ -1773,7 +1773,13 @@ void QBtSession::addTorrentsFromScanFolder(QStringList &pathList) {
   }
 }
 
-void QBtSession::setDefaultTempPath(QString temppath) {
+void QBtSession::setDefaultSavePath(const QString &savepath) {
+  if (defaultSavePath == savepath || savepath.isEmpty())
+    return;
+  defaultSavePath = QDir::fromNativeSeparators(savepath);
+}
+
+void QBtSession::setDefaultTempPath(const QString &temppath) {
   if (defaultTempPath == temppath)
     return;
   if (temppath.isEmpty()) {
@@ -1799,13 +1805,13 @@ void QBtSession::setDefaultTempPath(QString temppath) {
       QTorrentHandle h = QTorrentHandle(*torrentIT);
       if (!h.is_valid()) continue;
       if (!h.is_seed()) {
-        QString torrent_tmp_path = temppath.replace("\\", "/");
-        qDebug("Moving torrent to its temp save path: %s", qPrintable(torrent_tmp_path));
+        QString torrent_tmp_path = QDir::fromNativeSeparators(temppath);
+        qDebug("Moving torrent to its temp save path: %s", qPrintable(fsutils::toDisplayPath(torrent_tmp_path)));
         h.move_storage(torrent_tmp_path);
       }
     }
   }
-  defaultTempPath = temppath;
+  defaultTempPath = QDir::fromNativeSeparators(temppath);
 }
 
 void QBtSession::appendqBextensionToTorrent(const QTorrentHandle &h, bool append) {

src/qtlibtorrent/qbtsession.h

@@ -147,7 +147,8 @@ public slots:
   void setDHTPort(int dht_port);
   void setProxySettings(libtorrent::proxy_settings proxySettings);
   void setSessionSettings(const libtorrent::session_settings &sessionSettings);
-  void setDefaultTempPath(QString temppath);
+  void setDefaultSavePath(const QString &savepath);
+  void setDefaultTempPath(const QString &temppath);
   void setAppendLabelToSavePath(bool append);
   void appendLabelToTorrentSavePath(const QTorrentHandle &h);
   void changeLabelInTorrentSavePath(const QTorrentHandle &h, QString old_label, QString new_label);