diff --git a/NEWS.md b/NEWS.md
index 9e5b01c9..0db48ed1 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -13,6 +13,7 @@ Red Panda C++ Version 1.0.4
   - enhancement: add Portugese translation
   - fix: crash when eval statements like "fsm::stack fsm;"
   - enhancement: add Traditional Chinese translation
+  - fix: index of the longest line not correctly updated ( which will cause selection errors)
 
 Red Panda C++ Version 1.0.3
   - fix: when oj problem grabbed by competitive companion received,
diff --git a/RedPandaIDE/qsynedit/TextBuffer.cpp b/RedPandaIDE/qsynedit/TextBuffer.cpp
index ef119d34..2090918a 100644
--- a/RedPandaIDE/qsynedit/TextBuffer.cpp
+++ b/RedPandaIDE/qsynedit/TextBuffer.cpp
@@ -398,6 +398,8 @@ void SynEditStringList::deleteAt(int Index)
     beginUpdate();
     if (mIndexOfLongestLine == Index)
         mIndexOfLongestLine = -1;
+    else if (mIndexOfLongestLine>Index)
+        mIndexOfLongestLine -= 1;
     mList.removeAt(Index);
     emit deleted(Index,1);
     endUpdate();
@@ -426,9 +428,11 @@ void SynEditStringList::putString(int Index, const QString &s, bool notify) {
             ListIndexOutOfBounds(Index);
         }
         beginUpdate();
-        mIndexOfLongestLine = -1;
+        int oldColumns = mList[Index]->fColumns;
         mList[Index]->fString = s;
-        mList[Index]->fColumns = -1;
+        calculateLineColumns(Index);
+        if (oldColumns>mList[Index]->fColumns)
+            mIndexOfLongestLine = -1;
         if (notify)
             emit putted(Index,1);
         endUpdate();
diff --git a/RedPandaIDE/settingsdialog/projectcompileparamaterswidget.cpp b/RedPandaIDE/settingsdialog/projectcompileparamaterswidget.cpp
index ac1f3ee8..4a6dfda3 100644
--- a/RedPandaIDE/settingsdialog/projectcompileparamaterswidget.cpp
+++ b/RedPandaIDE/settingsdialog/projectcompileparamaterswidget.cpp
@@ -18,6 +18,9 @@
 #include "ui_projectcompileparamaterswidget.h"
 #include "../mainwindow.h"
 #include "../project.h"
+#include "../iconsmanager.h"
+
+#include <QFileDialog>
 
 ProjectCompileParamatersWidget::ProjectCompileParamatersWidget(const QString &name, const QString &group, QWidget *parent) :
     SettingsWidget(name,group,parent),
@@ -45,3 +48,29 @@ void ProjectCompileParamatersWidget::doSave()
     pMainWindow->project()->options().linkerCmd = ui->txtLinker->toPlainText();
     pMainWindow->project()->saveOptions();
 }
+
+void ProjectCompileParamatersWidget::on_btnChooseLib_clicked()
+{
+#ifdef Q_OS_WIN
+    QString filter = tr("Library Files (*.a *.lib)");
+#else
+    QString filter = tr("Library Files (*.a)");
+#endif
+
+    QStringList files = QFileDialog::getOpenFileNames(
+                this,
+                tr("Add Library Files"),
+                filter
+                );
+    if (!files.isEmpty()) {
+        foreach (const QString& file,files) {
+            ui->txtLinker->appendPlainText(" "+genMakePath1(file));
+        }
+    }
+}
+
+void ProjectCompileParamatersWidget::updateIcons(const QSize &size)
+{
+    pIconsManager->setIcon(ui->btnChooseLib, IconsManager::ACTION_MISC_FOLDER);
+}
+
diff --git a/RedPandaIDE/settingsdialog/projectcompileparamaterswidget.ui b/RedPandaIDE/settingsdialog/projectcompileparamaterswidget.ui
index a536b31e..b1fe6cad 100644
--- a/RedPandaIDE/settingsdialog/projectcompileparamaterswidget.ui
+++ b/RedPandaIDE/settingsdialog/projectcompileparamaterswidget.ui
@@ -24,7 +24,7 @@
    <item>
     <widget class="QTabWidget" name="tabCommands">
      <property name="currentIndex">
-      <number>0</number>
+      <number>2</number>
      </property>
      <widget class="QWidget" name="tab">
       <attribute name="title">
@@ -74,7 +74,7 @@
       <attribute name="title">
        <string>Linker</string>
       </attribute>
-      <layout class="QHBoxLayout" name="horizontalLayout_3">
+      <layout class="QVBoxLayout" name="verticalLayout_2">
        <property name="leftMargin">
         <number>5</number>
        </property>
@@ -90,6 +90,38 @@
        <item>
         <widget class="QPlainTextEdit" name="txtLinker"/>
        </item>
+       <item>
+        <widget class="QFrame" name="frame">
+         <property name="frameShape">
+          <enum>QFrame::StyledPanel</enum>
+         </property>
+         <property name="frameShadow">
+          <enum>QFrame::Raised</enum>
+         </property>
+         <layout class="QHBoxLayout" name="horizontalLayout_3">
+          <item>
+           <spacer name="horizontalSpacer">
+            <property name="orientation">
+             <enum>Qt::Horizontal</enum>
+            </property>
+            <property name="sizeHint" stdset="0">
+             <size>
+              <width>40</width>
+              <height>20</height>
+             </size>
+            </property>
+           </spacer>
+          </item>
+          <item>
+           <widget class="QToolButton" name="btnChooseLib">
+            <property name="text">
+             <string>...</string>
+            </property>
+           </widget>
+          </item>
+         </layout>
+        </widget>
+       </item>
       </layout>
      </widget>
     </widget>