diff --git a/NEWS.md b/NEWS.md
index aeee3e6f..32d3668b 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -22,6 +22,8 @@ Red Panda C++ Version 2.24
   - fix: Wrong code suggestion while inputing numbers in assembly files.
   - fix: Defines in all files are wrongly cleared when reparsing.
   - change: New file created by file template is set as unmodified by default.
+  - change: Remove option "clear all symbols when current editor is hidden".
+  - fix: When opening multiple files, only the active file should be parsed.
 
 Red Panda C++ Version 2.23
 
diff --git a/RedPandaIDE/editor.cpp b/RedPandaIDE/editor.cpp
index 4bf058e8..4da3faec 100644
--- a/RedPandaIDE/editor.cpp
+++ b/RedPandaIDE/editor.cpp
@@ -217,9 +217,12 @@ Editor::Editor(QWidget *parent, const QString& filename,
             this, &Editor::onScrollBarValueChanged);
     mInited=true;
 
-    reparse(false);
-    checkSyntaxInBack();
-    reparseTodo();
+//    if (!pMainWindow->openingFiles()
+//            && !pMainWindow->openingProject()) {
+//        reparse(false);
+//        checkSyntaxInBack();
+//        reparseTodo();
+//    }
 }
 
 Editor::~Editor() {
@@ -1386,7 +1389,8 @@ void Editor::showEvent(QShowEvent */*event*/)
                 &CppParser::onEndParsing,
                 this,
                 &Editor::onEndParsing);
-        reparse(false);
+        if (!pMainWindow->openingFiles() && !pMainWindow->openingProject())
+            reparse(false);
     }
     if (mParentPageControl) {
         pMainWindow->debugger()->setIsForProject(inProject());
@@ -1395,7 +1399,9 @@ void Editor::showEvent(QShowEvent */*event*/)
     }
 
     if (!pMainWindow->isClosingAll()
-                && !pMainWindow->isQuitting()) {
+                && !pMainWindow->isQuitting()
+            && !pMainWindow->openingFiles()
+            && !pMainWindow->openingProject()) {
         if (!inProject() || !pMainWindow->closingProject()) {
             checkSyntaxInBack();
             reparseTodo();
@@ -1418,12 +1424,13 @@ void Editor::showEvent(QShowEvent */*event*/)
 
 void Editor::hideEvent(QHideEvent */*event*/)
 {
-    if (pSettings->codeCompletion().clearWhenEditorHidden()
-            && !inProject() && mParser
-            && !pMainWindow->isMinimized()) {
-        //recreate a parser, to totally clean memories the parser uses;
-        resetCppParser(mParser);
-    }
+//    if (pSettings->codeCompletion().clearWhenEditorHidden()
+//            && !inProject() && mParser
+//            && !pMainWindow->isMinimized()) {
+//        //recreate a parser, to totally clean memories the parser uses;
+//        if (!pMainWindow->openingFiles() && !pMainWindow->openingProject())
+//            resetCppParser(mParser);
+//    }
     if (mParser) {
         disconnect(mParser.get(),
                 &CppParser::onEndParsing,
diff --git a/RedPandaIDE/mainwindow.cpp b/RedPandaIDE/mainwindow.cpp
index 0ead2bec..3182e402 100644
--- a/RedPandaIDE/mainwindow.cpp
+++ b/RedPandaIDE/mainwindow.cpp
@@ -117,6 +117,8 @@ MainWindow::MainWindow(QWidget *parent)
       mSearchInFilesDialog{nullptr},
       mSearchDialog{nullptr},
       mQuitting{false},
+      mOpeningFiles{false},
+      mOpeningProject{false},
       mClosingProject{false},
       mCheckSyntaxInBack{false},
       mShouldRemoveAllSettings{false},
@@ -445,8 +447,8 @@ MainWindow::MainWindow(QWidget *parent)
     connect(ui->EditorTabsRight, &EditorsTabWidget::middleButtonClicked,
             this, &MainWindow::on_EditorTabsRight_tabCloseRequested);
 
-    //git menu
 #ifdef ENABLE_VCS
+    //git menu
     connect(ui->menuGit, &QMenu::aboutToShow,
             this, &MainWindow::updateVCSActions);
 #endif
@@ -1442,6 +1444,10 @@ void MainWindow::setProjectCurrentFile(const QString &filename)
 
 void MainWindow::openFiles(const QStringList &files)
 {
+    mOpeningFiles=true;
+    auto action=finally([this]{
+        mOpeningFiles=false;
+    });
     mEditorList->beginUpdate();
     mOpenningFiles = true;
     auto end = finally([this] {
@@ -1464,8 +1470,12 @@ void MainWindow::openFiles(const QStringList &files)
     }
     mEditorList->endUpdate();
     Editor* e=mEditorList->getEditor();
-    if (e)
+    if (e) {
+        e->reparse(false);
+        e->checkSyntaxInBack();
+        e->reparseTodo();
         e->activate();
+    }
 }
 
 Editor* MainWindow::openFile(QString filename, bool activate, QTabWidget* page)
@@ -1523,6 +1533,10 @@ Editor* MainWindow::openFile(QString filename, bool activate, QTabWidget* page)
 
 void MainWindow::openProject(QString filename, bool openFiles)
 {
+    mOpeningProject=true;
+    auto action=finally([this]{
+        mOpeningProject=false;
+    });
     if (!fileExists(filename)) {
         return;
     }
@@ -3189,6 +3203,10 @@ bool MainWindow::saveLastOpens()
 
 void MainWindow::loadLastOpens()
 {
+    mOpeningFiles=true;
+    auto action=finally([this]{
+        mOpeningFiles=false;
+    });
     QString filename = includeTrailingPathDelimiter(pSettings->dirs().config()) + DEV_LASTOPENS_FILE;
     if (!fileExists(filename))
         return;
@@ -3275,8 +3293,15 @@ void MainWindow::loadLastOpens()
         updateEditorActions();
         //updateForEncodingInfo();
     }
-    if (focusedEditor)
+    if (!focusedEditor) {
+        focusedEditor = mEditorList->getEditor();
+    }
+    if (focusedEditor) {
+        focusedEditor->reparse(false);
+        focusedEditor->checkSyntaxInBack();
+        focusedEditor->reparseTodo();
         focusedEditor->activate();
+    }
 }
 
 void MainWindow::updateTools()
@@ -7548,7 +7573,8 @@ void MainWindow::reparseNonProjectEditors()
     for (int i=0;i<mEditorList->pageCount();i++) {
         Editor* e=(*mEditorList)[i];
         if (!e->inProject()) {
-            if (!pSettings->codeCompletion().clearWhenEditorHidden() || e->isVisible()) {
+//            if (!pSettings->codeCompletion().clearWhenEditorHidden() || e->isVisible()) {
+            if (e->isVisible()) {
                 e->reparse(true);
                 e->checkSyntaxInBack();
             }
@@ -7959,6 +7985,7 @@ void MainWindow::on_actionRename_Symbol_triggered()
     refactor.renameSymbol(editor,oldCaretXY,newWord);
     editor->reparse(true);
     editor->checkSyntaxInBack();
+    editor->reparseTodo();
 }
 
 
@@ -10014,3 +10041,13 @@ void MainWindow::on_actionTurtle_Graphics_Manual_triggered()
     QDesktopServices::openUrl(QUrl("https://zhuanlan.zhihu.com/p/538666844"));
 }
 
+bool MainWindow::openingProject() const
+{
+    return mOpeningProject;
+}
+
+bool MainWindow::openingFiles() const
+{
+    return mOpeningFiles;
+}
+
diff --git a/RedPandaIDE/mainwindow.h b/RedPandaIDE/mainwindow.h
index 8cd509ea..ea7c34ee 100644
--- a/RedPandaIDE/mainwindow.h
+++ b/RedPandaIDE/mainwindow.h
@@ -872,6 +872,8 @@ private:
     SearchInFileDialog *mSearchInFilesDialog;
     SearchDialog *mSearchDialog;
     bool mQuitting;
+    bool mOpeningFiles;
+    bool mOpeningProject;
     bool mClosingProject;
     QElapsedTimer mParserTimer;
     QFileSystemWatcher mFileSystemWatcher;
@@ -1028,6 +1030,8 @@ public:
     bool isQuitting() const;
     const std::shared_ptr<VisitHistoryManager> &visitHistoryManager() const;
     bool closingProject() const;
+    bool openingFiles() const;
+    bool openingProject() const;
 };
 
 extern MainWindow* pMainWindow;
diff --git a/RedPandaIDE/parser/cppparser.cpp b/RedPandaIDE/parser/cppparser.cpp
index 843d6a8e..33adb253 100644
--- a/RedPandaIDE/parser/cppparser.cpp
+++ b/RedPandaIDE/parser/cppparser.cpp
@@ -6526,6 +6526,7 @@ void parseFile(PCppParser parser, const QString& fileName, bool inProject, bool
         return;
     if (!parser->enabled())
         return;
+//    qDebug()<<"parsing "<<fileName;
     //delete when finished
     CppFileParserThread* thread = new CppFileParserThread(parser,fileName,inProject,onlyIfNotParsed,updateView);
     thread->connect(thread,
diff --git a/RedPandaIDE/settings.cpp b/RedPandaIDE/settings.cpp
index 557d06b4..51766c78 100644
--- a/RedPandaIDE/settings.cpp
+++ b/RedPandaIDE/settings.cpp
@@ -4166,32 +4166,32 @@ void Settings::CodeCompletion::setShowCodeIns(bool newShowCodeIns)
     mShowCodeIns = newShowCodeIns;
 }
 
-bool Settings::CodeCompletion::clearWhenEditorHidden()
-{
-    if (!mShareParser) {
-#ifdef Q_OS_WIN
-        MEMORYSTATUSEX statex;
-        statex.dwLength = sizeof (statex);
-        GlobalMemoryStatusEx (&statex);
+//bool Settings::CodeCompletion::clearWhenEditorHidden()
+//{
+//    if (!mShareParser) {
+//#ifdef Q_OS_WIN
+//        MEMORYSTATUSEX statex;
+//        statex.dwLength = sizeof (statex);
+//        GlobalMemoryStatusEx (&statex);
 
-        if (statex.ullAvailPhys < (long long int)2*1024*1024*1024) {
-            return true;
-        }
-#elif defined(Q_OS_LINUX)
-        struct sysinfo si;
-        sysinfo(&si);
-        if (si.freeram < (long long int)2*1024*1024*1024) {
-            return true;
-        }
-#endif
-    }
-    return mClearWhenEditorHidden;
-}
+//        if (statex.ullAvailPhys < (long long int)2*1024*1024*1024) {
+//            return true;
+//        }
+//#elif defined(Q_OS_LINUX)
+//        struct sysinfo si;
+//        sysinfo(&si);
+//        if (si.freeram < (long long int)2*1024*1024*1024) {
+//            return true;
+//        }
+//#endif
+//    }
+//    return mClearWhenEditorHidden;
+//}
 
-void Settings::CodeCompletion::setClearWhenEditorHidden(bool newClearWhenEditorHidden)
-{
-    mClearWhenEditorHidden = newClearWhenEditorHidden;
-}
+//void Settings::CodeCompletion::setClearWhenEditorHidden(bool newClearWhenEditorHidden)
+//{
+//    mClearWhenEditorHidden = newClearWhenEditorHidden;
+//}
 
 int Settings::CodeCompletion::minCharRequired() const
 {
@@ -4357,7 +4357,7 @@ void Settings::CodeCompletion::doSave()
     saveValue("ignore_case",mIgnoreCase);
     saveValue("append_func",mAppendFunc);
     saveValue("show_code_ins",mShowCodeIns);
-    saveValue("clear_when_editor_hidden",mClearWhenEditorHidden);
+    //saveValue("clear_when_editor_hidden",mClearWhenEditorHidden);
     saveValue("min_char_required",mMinCharRequired);
     saveValue("hide_symbols_start_with_two_underline", mHideSymbolsStartsWithTwoUnderLine);
     saveValue("hide_symbols_start_with_underline", mHideSymbolsStartsWithUnderLine);
@@ -4412,7 +4412,7 @@ void Settings::CodeCompletion::doLoad()
 //        shouldShare = false;
 //    }
 //#endif
-    mClearWhenEditorHidden = boolValue("clear_when_editor_hidden",doClear);
+    //mClearWhenEditorHidden = boolValue("clear_when_editor_hidden",doClear);
     mShareParser = boolValue("share_parser",shouldShare);
 }
 
diff --git a/RedPandaIDE/settings.h b/RedPandaIDE/settings.h
index bd0e9937..c31b0617 100644
--- a/RedPandaIDE/settings.h
+++ b/RedPandaIDE/settings.h
@@ -653,8 +653,8 @@ public:
         bool showCodeIns() const;
         void setShowCodeIns(bool newShowCodeIns);
 
-        bool clearWhenEditorHidden();
-        void setClearWhenEditorHidden(bool newClearWhenEditorHidden);
+        //bool clearWhenEditorHidden();
+        //void setClearWhenEditorHidden(bool newClearWhenEditorHidden);
 
         int minCharRequired() const;
         void setMinCharRequired(int newMinCharRequired);
@@ -684,7 +684,7 @@ public:
         int mMinCharRequired;
         bool mHideSymbolsStartsWithTwoUnderLine;
         bool mHideSymbolsStartsWithUnderLine;
-        bool mClearWhenEditorHidden;
+        //bool mClearWhenEditorHidden;
         bool mShareParser;
 
         // _Base interface
diff --git a/RedPandaIDE/settingsdialog/editorcodecompletionwidget.cpp b/RedPandaIDE/settingsdialog/editorcodecompletionwidget.cpp
index 5d770003..a8eeb6b9 100644
--- a/RedPandaIDE/settingsdialog/editorcodecompletionwidget.cpp
+++ b/RedPandaIDE/settingsdialog/editorcodecompletionwidget.cpp
@@ -26,6 +26,7 @@ EditorCodeCompletionWidget::EditorCodeCompletionWidget(const QString& name, cons
     ui(new Ui::EditorCodeCompletionWidget)
 {
     ui->setupUi(this);
+    ui->chkClearWhenEditorHidden->setVisible(false);
 }
 
 EditorCodeCompletionWidget::~EditorCodeCompletionWidget()
@@ -50,7 +51,7 @@ void EditorCodeCompletionWidget::doLoad()
     ui->chkIgnoreCases->setChecked(pSettings->codeCompletion().ignoreCase());
     ui->chkAppendFunc->setChecked(pSettings->codeCompletion().appendFunc());
     ui->chkShowCodeIns->setChecked(pSettings->codeCompletion().showCodeIns());
-    ui->chkClearWhenEditorHidden->setChecked(pSettings->codeCompletion().clearWhenEditorHidden());
+//    ui->chkClearWhenEditorHidden->setChecked(pSettings->codeCompletion().clearWhenEditorHidden());
     ui->chkHideSymbolsStartWithTwoUnderline->setChecked(pSettings->codeCompletion().hideSymbolsStartsWithTwoUnderLine());
     ui->chkHideSymbolsStartWithUnderline->setChecked(pSettings->codeCompletion().hideSymbolsStartsWithUnderLine());
 
@@ -78,7 +79,7 @@ void EditorCodeCompletionWidget::doSave()
     pSettings->codeCompletion().setShowCodeIns(ui->chkShowCodeIns->isChecked());
     pSettings->codeCompletion().setMinCharRequired(ui->spinMinCharRequired->value());
 
-    pSettings->codeCompletion().setClearWhenEditorHidden(ui->chkClearWhenEditorHidden->isChecked());
+    //pSettings->codeCompletion().setClearWhenEditorHidden(ui->chkClearWhenEditorHidden->isChecked());
 
     pSettings->codeCompletion().setHideSymbolsStartsWithTwoUnderLine(ui->chkHideSymbolsStartWithTwoUnderline->isChecked());
     pSettings->codeCompletion().setHideSymbolsStartsWithUnderLine(ui->chkHideSymbolsStartWithUnderline->isChecked());
diff --git a/RedPandaIDE/settingsdialog/environmentperformancewidget.cpp b/RedPandaIDE/settingsdialog/environmentperformancewidget.cpp
index 576ed84c..93f705ef 100644
--- a/RedPandaIDE/settingsdialog/environmentperformancewidget.cpp
+++ b/RedPandaIDE/settingsdialog/environmentperformancewidget.cpp
@@ -23,6 +23,7 @@ EnvironmentPerformanceWidget::EnvironmentPerformanceWidget(const QString& name,
     ui(new Ui::EnvironmentPerformanceWidget)
 {
     ui->setupUi(this);
+    ui->chkClearWhenEditorHidden->setVisible(false);
 }
 
 EnvironmentPerformanceWidget::~EnvironmentPerformanceWidget()
@@ -32,7 +33,7 @@ EnvironmentPerformanceWidget::~EnvironmentPerformanceWidget()
 
 void EnvironmentPerformanceWidget::doLoad()
 {
-    ui->chkClearWhenEditorHidden->setChecked(pSettings->codeCompletion().clearWhenEditorHidden());
+//    ui->chkClearWhenEditorHidden->setChecked(pSettings->codeCompletion().clearWhenEditorHidden());
 //#ifdef Q_OS_WIN
 //    MEMORYSTATUSEX statex;
 
@@ -58,7 +59,7 @@ void EnvironmentPerformanceWidget::doLoad()
 
 void EnvironmentPerformanceWidget::doSave()
 {
-    pSettings->codeCompletion().setClearWhenEditorHidden(ui->chkClearWhenEditorHidden->isChecked());
+    //pSettings->codeCompletion().setClearWhenEditorHidden(ui->chkClearWhenEditorHidden->isChecked());
     pSettings->codeCompletion().setShareParser(ui->chkEditorsShareParser->isChecked());
 
     pSettings->codeCompletion().save();