diff --git a/BallanceTASEditor.csproj b/BallanceTASEditor.csproj
index ed15637..71587e1 100644
--- a/BallanceTASEditor.csproj
+++ b/BallanceTASEditor.csproj
@@ -34,6 +34,7 @@
     <WarningLevel>4</WarningLevel>
   </PropertyGroup>
   <ItemGroup>
+    <Reference Include="Microsoft.VisualBasic" />
     <Reference Include="System" />
     <Reference Include="System.Data" />
     <Reference Include="System.Xml" />
@@ -56,11 +57,13 @@
       <Generator>MSBuild:Compile</Generator>
       <SubType>Designer</SubType>
     </ApplicationDefinition>
+    <Compile Include="UI\SelectionHelp.cs" />
     <Compile Include="UI\StyleConverter.cs" />
     <Compile Include="UI\TASFlow.xaml.cs">
       <DependentUpon>TASFlow.xaml</DependentUpon>
     </Compile>
     <Compile Include="UI\TASViewer.cs" />
+    <Compile Include="UI\Util.cs" />
     <Page Include="MainWindow.xaml">
       <Generator>MSBuild:Compile</Generator>
       <SubType>Designer</SubType>
diff --git a/Core/TASStruct.cs b/Core/TASStruct.cs
index 5391115..92d93ab 100644
--- a/Core/TASStruct.cs
+++ b/Core/TASStruct.cs
@@ -131,16 +131,16 @@ namespace BallanceTASEditor.Core.TASStruct {
         public const int FRAMEDATA_OFFSET_KEY_STATES = 4;
     }
 
-    public enum FrameDataField {
-        Key_Up,
-        Key_Down,
-        Key_Left,
-        Key_Right,
-        Key_Shift,
-        Key_Space,
-        Key_Q,
-        Key_Esc,
-        Key_Enter
+    public enum FrameDataField : int {
+        Key_Up = 0,
+        Key_Down = 1,
+        Key_Left = 2,
+        Key_Right = 3,
+        Key_Shift = 4,
+        Key_Space = 5,
+        Key_Q = 6,
+        Key_Esc = 7,
+        Key_Enter = 8
     }
 
 }
diff --git a/MainWindow.xaml b/MainWindow.xaml
index e783f9f..e0ad970 100644
--- a/MainWindow.xaml
+++ b/MainWindow.xaml
@@ -23,7 +23,7 @@
                 <MenuItem x:Name="uiMenu_File_Close" Header="Close" Click="funcMenu_File_Close"/>
             </MenuItem>
             <MenuItem Header="Display">
-                <MenuItem x:Name="uiMenu_Display_ItemCount" Header="Item Count"/>
+                <MenuItem x:Name="uiMenu_Display_ItemCount" Header="Item Count" Click="funcMenu_Display_ItemCount"/>
             </MenuItem>
             <MenuItem Header="Help">
                 <MenuItem x:Name="uiMenu_Help_ReportBugs" Header="Report bugs" Click="funcMenu_Help_ReportBugs"/>
@@ -41,7 +41,7 @@
             </Grid.RowDefinitions>
 
             <StackPanel Orientation="Horizontal" Grid.Row="0" Grid.ColumnSpan="2">
-                <Button x:Name="uiBtn_Select" Margin="5" Padding="5">
+                <Button x:Name="uiBtn_Cursor" Margin="5" Padding="5" Click="funcBtn_Cursor">
                     <StackPanel Orientation="Horizontal">
                         <Viewbox Width="24" Height="24">
                             <Canvas Width="24" Height="24">
@@ -51,7 +51,7 @@
                         <TextBlock Text="Select mode" VerticalAlignment="Center"/>
                     </StackPanel>
                 </Button>
-                <Button x:Name="uiBtn_Fill" Margin="5" Padding="5">
+                <Button x:Name="uiBtn_Fill" Margin="5" Padding="5" Click="funcBtn_Fill">
                     <StackPanel Orientation="Horizontal">
                         <Viewbox Width="24" Height="24">
                             <Canvas Width="24" Height="24">
@@ -61,7 +61,7 @@
                         <TextBlock Text="Fill mode" VerticalAlignment="Center"/>
                     </StackPanel>
                 </Button>
-                <Button x:Name="uiBtn_Draw" Margin="5" Padding="5">
+                <Button x:Name="uiBtn_Overwrite" Margin="5" Padding="5" Click="funcBtn_Overwrite">
                     <StackPanel Orientation="Horizontal">
                         <Viewbox Width="24" Height="24">
                             <Canvas Width="24" Height="24">
@@ -127,13 +127,13 @@
 
         </Grid>
 
-        <StatusBar Grid.Row="2">
-            <TextBlock Text="Select mode"/>
-            <TextBlock Text="Fill mode"/>
-            <TextBlock Text="Draw mode"/>
+        <StatusBar x:Name="uiStatusbar" Grid.Row="2">
+            <TextBlock x:Name="uiStatusbar_Mode_Cursor" Text="Select mode"/>
+            <TextBlock x:Name="uiStatusbar_Mode_Fill" Text="Fill mode"/>
+            <TextBlock x:Name="uiStatusbar_Mode_Overwrite" Text="Draw mode"/>
             <Separator/>
             <TextBlock Text="Selected: "/>
-            <TextBlock Text="aaa"/>
+            <TextBlock x:Name="uiStatusbar_Selected" Text="-"/>
         </StatusBar>
 
     </Grid>
diff --git a/MainWindow.xaml.cs b/MainWindow.xaml.cs
index 931bf5b..88e18be 100644
--- a/MainWindow.xaml.cs
+++ b/MainWindow.xaml.cs
@@ -22,15 +22,27 @@ namespace BallanceTASEditor {
     public partial class MainWindow : Window {
         public MainWindow() {
             InitializeComponent();
+
+            // bind event without xaml due to xaml shit design
+            uiTASData.uiDataMenu_Set.Click += funcDataMenu_Set;
+            uiTASData.uiDataMenu_Unset.Click += funcDataMenu_Unset;
+            uiTASData.uiDataMenu_Copy.Click += funcDataMenu_Copy;
+            uiTASData.uiDataMenu_Delete.Click += funcDataMenu_Delete;
+            uiTASData.uiDataMenu_PasteAfter.Click += funcDataMenu_PasteAfter;
+            uiTASData.uiDataMenu_PasteBefore.Click += funcDataMenu_PasteBefore;
+            uiTASData.uiDataMenu_AddAfter.Click += funcDataMenu_AddAfter;
+            uiTASData.uiDataMenu_AddBefore.Click += funcDataMenu_AddBefore;
+
             RefreshUI(false);
         }
 
+
         TASFile mFile;
         TASViewer mViewer;
 
         #region ui func
 
-        // menu
+        // =========================== menu
         private void funcMenu_Help_ReportBugs(object sender, RoutedEventArgs e) {
             System.Diagnostics.Process.Start("https://github.com/yyc12345/BallanceTASEditor/issues");
         }
@@ -43,8 +55,9 @@ namespace BallanceTASEditor {
             var file = DialogUtil.OpenFileDialog();
             if (file == "") return;
             mFile = new TASFile(file);
-            mViewer = new TASViewer(mFile, uiTASSlider, uiTASData);
+            mViewer = new TASViewer(mFile, uiTASSlider, uiTASData, uiStatusbar_Selected);
             RefreshUI(true);
+            ChangeToolMode(ToolMode.Cursor);
         }
 
         private void funcMenu_File_Save(object sender, RoutedEventArgs e) {
@@ -65,9 +78,98 @@ namespace BallanceTASEditor {
             RefreshUI(false);
         }
 
+        private void funcMenu_Display_ItemCount(object sender, RoutedEventArgs e) {
+            int newvalue = 0;
+            if (DialogUtil.InputNumber("Input new count (>=5 && <=30)", 5, 30, ref newvalue)) {
+                mViewer.ChangeListLength(newvalue);
+            }
+        }
+
+        // =========================== btn
+        private void funcBtn_Cursor(object sender, RoutedEventArgs e) {
+            ChangeToolMode(ToolMode.Cursor);
+        }
+
+        private void funcBtn_Fill(object sender, RoutedEventArgs e) {
+            ChangeToolMode(ToolMode.Fill);
+        }
+
+        private void funcBtn_Overwrite(object sender, RoutedEventArgs e) {
+            ChangeToolMode(ToolMode.Overwrite);
+        }
 
         #endregion
 
+        #region data menu
+
+        private void funcDataMenu_AddBefore(object sender, RoutedEventArgs e) {
+            throw new NotImplementedException();
+        }
+
+        private void funcDataMenu_AddAfter(object sender, RoutedEventArgs e) {
+            throw new NotImplementedException();
+        }
+
+        private void funcDataMenu_PasteBefore(object sender, RoutedEventArgs e) {
+            throw new NotImplementedException();
+        }
+
+        private void funcDataMenu_PasteAfter(object sender, RoutedEventArgs e) {
+            throw new NotImplementedException();
+        }
+
+        private void funcDataMenu_Delete(object sender, RoutedEventArgs e) {
+            throw new NotImplementedException();
+        }
+
+        private void funcDataMenu_Copy(object sender, RoutedEventArgs e) {
+            throw new NotImplementedException();
+        }
+
+        private void funcDataMenu_Unset(object sender, RoutedEventArgs e) {
+            throw new NotImplementedException();
+        }
+
+        private void funcDataMenu_Set(object sender, RoutedEventArgs e) {
+            throw new NotImplementedException();
+        }
+
+        #endregion
+
+        private void ChangeToolMode(ToolMode mode) {
+            switch (mode) {
+                case ToolMode.Cursor:
+                    uiBtn_Cursor.IsEnabled = false;
+                    uiBtn_Fill.IsEnabled = true;
+                    uiBtn_Overwrite.IsEnabled = true;
+
+                    uiStatusbar_Mode_Cursor.Visibility = Visibility.Visible;
+                    uiStatusbar_Mode_Fill.Visibility = Visibility.Collapsed;
+                    uiStatusbar_Mode_Overwrite.Visibility = Visibility.Collapsed;
+                    break;
+                case ToolMode.Fill:
+                    uiBtn_Cursor.IsEnabled = true;
+                    uiBtn_Fill.IsEnabled = false;
+                    uiBtn_Overwrite.IsEnabled = true;
+
+                    uiStatusbar_Mode_Cursor.Visibility = Visibility.Collapsed;
+                    uiStatusbar_Mode_Fill.Visibility = Visibility.Visible;
+                    uiStatusbar_Mode_Overwrite.Visibility = Visibility.Collapsed;
+                    break;
+                case ToolMode.Overwrite:
+                    uiBtn_Cursor.IsEnabled = true;
+                    uiBtn_Fill.IsEnabled = true;
+                    uiBtn_Overwrite.IsEnabled = false;
+
+                    uiStatusbar_Mode_Cursor.Visibility = Visibility.Collapsed;
+                    uiStatusbar_Mode_Fill.Visibility = Visibility.Collapsed;
+                    uiStatusbar_Mode_Overwrite.Visibility = Visibility.Visible;
+                    break;
+            }
+
+            mViewer.ChangeToolMode(mode);
+        }
+
         private void RefreshUI(bool isFileOpened) {
             if (isFileOpened) {
                 uiEditorPanel.Visibility = Visibility.Visible;
@@ -77,6 +179,10 @@ namespace BallanceTASEditor {
                 uiMenu_File_Save.IsEnabled = true;
                 uiMenu_File_SaveAs.IsEnabled = true;
                 uiMenu_File_Close.IsEnabled = true;
+
+                uiMenu_Display_ItemCount.IsEnabled = true;
+
+                uiStatusbar.Visibility = Visibility.Visible;
             } else {
                 uiEditorPanel.Visibility = Visibility.Collapsed;
                 uiEditorNote.Visibility = Visibility.Visible;
@@ -85,6 +191,10 @@ namespace BallanceTASEditor {
                 uiMenu_File_Save.IsEnabled = false;
                 uiMenu_File_SaveAs.IsEnabled = false;
                 uiMenu_File_Close.IsEnabled = false;
+
+                uiMenu_Display_ItemCount.IsEnabled = false;
+
+                uiStatusbar.Visibility = Visibility.Collapsed;
             }
         }
 
diff --git a/UI/DialogUtil.cs b/UI/DialogUtil.cs
index e6d1a13..84c8503 100644
--- a/UI/DialogUtil.cs
+++ b/UI/DialogUtil.cs
@@ -1,4 +1,5 @@
-using System;
+using Microsoft.VisualBasic;
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
@@ -15,7 +16,7 @@ namespace BallanceTASEditor.UI {
             if (!(bool)op.ShowDialog()) return "";
             return op.FileName;
         }
-        
+
         public static string SaveFileDialog() {
             Microsoft.Win32.SaveFileDialog op = new Microsoft.Win32.SaveFileDialog();
             op.RestoreDirectory = true;
@@ -29,5 +30,17 @@ namespace BallanceTASEditor.UI {
             return (result == MessageBoxResult.Yes);
         }
 
+        public static bool InputNumber(string title, int min, int max, ref int result) {
+            while (true) {
+                var dialog = Interaction.InputBox(title, "Input number", "");
+                if (dialog == "") return false;
+                if (int.TryParse(dialog, out result)) {
+                    if (result <= max && result >= min) break;
+                }
+                MessageBox.Show("Invalid number. Please input again", "Warning", MessageBoxButton.OK, MessageBoxImage.Warning);
+            }
+            return true;
+        }
+
     }
 }
diff --git a/UI/SelectionHelp.cs b/UI/SelectionHelp.cs
new file mode 100644
index 0000000..d1049cb
--- /dev/null
+++ b/UI/SelectionHelp.cs
@@ -0,0 +1,148 @@
+using BallanceTASEditor.Core.TASStruct;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace BallanceTASEditor.UI {
+    public class SelectionHelp {
+        public SelectionHelp() {
+            SetMode(ToolMode.Cursor);
+        }
+
+        public event Action SelectionChanged;
+
+        ToolMode mMode;
+        FrameDataField mStartField;
+        FrameDataField mEndField;
+        long mStart;
+        bool mIsStartConfirmed;
+        long mEnd;
+        bool mIsEndConfirmed;
+
+        public void SetMode(ToolMode mode) {
+            switch (mode) {
+                case ToolMode.Cursor:
+                    mStart = 0;
+                    mEnd = 0;
+                    mIsStartConfirmed = false;
+                    mIsEndConfirmed = false;
+                    break;
+                case ToolMode.Fill:
+                    mStartField = FrameDataField.Key_Up;
+                    mEndField = FrameDataField.Key_Up;
+                    mStart = 0;
+                    mEnd = 0;
+                    mIsStartConfirmed = false;
+                    mIsEndConfirmed = false;
+                    break;
+                case ToolMode.Overwrite:
+                    mStartField = FrameDataField.Key_Up;
+                    mStart = 0;
+                    mIsStartConfirmed = false;
+                    break;
+            }
+
+            mMode = mode;
+            OnSelectionChanged();
+        }
+
+        public void FirstClick(long index, FrameDataField field) {
+            mStartField = field;
+            mStart = index;
+            mIsStartConfirmed = true;
+            mIsEndConfirmed = false;
+
+            OnSelectionChanged();
+        }
+
+        public void LastClick(long index, FrameDataField field) {
+            if (mMode == ToolMode.Overwrite) return;
+            if (!mIsStartConfirmed) return;
+
+            mEndField = field;
+            mEnd = index;
+            mIsEndConfirmed = true;
+            OnSelectionChanged();
+        }
+
+        public void Reset() {
+            // reuse set mode to reset
+            SetMode(mMode);
+        }
+
+        public SelectionRange GetRange() {
+            if (mMode == ToolMode.Overwrite) throw new Exception("Read with wrong mode.");
+            if (!(mIsStartConfirmed && mIsEndConfirmed)) throw new Exception("Data is not ready to read");
+            return new SelectionRange(mStart, mEnd);
+        }
+
+        public SelectionRange GetFieldRange() {
+            if (mMode != ToolMode.Fill) throw new Exception("Read with wrong mode.");
+            if (!(mIsStartConfirmed && mIsEndConfirmed)) throw new Exception("Data is not ready to read");
+            return new SelectionRange((int)mStartField, (int)mEndField);
+        }
+
+        public long GetPoint() {
+            if (mMode == ToolMode.Fill) throw new Exception("Read with wrong mode.");
+            if (!mIsStartConfirmed) throw new Exception("Data is not ready to read");
+
+            if (mMode == ToolMode.Cursor) return mStart;
+            else {
+                // cursor mode
+                if (mIsStartConfirmed) return mStart;
+                else throw new Exception("Data is not ready to read");
+            }
+        }
+
+        public bool IsDataReady() {
+            switch (mMode) {
+                case ToolMode.Cursor:
+                case ToolMode.Fill:
+                    return (mIsStartConfirmed && mIsEndConfirmed);
+                case ToolMode.Overwrite:
+                    return mIsStartConfirmed;
+            }
+            return false;
+        }
+
+        public bool IsDataPartialReady() {
+            return (mMode == ToolMode.Cursor && mIsStartConfirmed && !mIsEndConfirmed);
+        }
+
+        public ToolMode GetToolMode() {
+            return mMode;
+        }
+
+        private void OnSelectionChanged() {
+            SelectionChanged?.Invoke();
+        }
+
+    }
+
+    public struct SelectionRange {
+        public SelectionRange(long value1, long value2) {
+            if (value1 > value2) {
+                start = value2;
+                end = value1;
+            } else {
+                start = value1;
+                end = value2;
+            }
+        }
+        public long start;
+        public long end;
+        public SelectionRange GetRelative(long refer) {
+            var res = new SelectionRange();
+            res.start = start - refer;
+            res.end = end - refer;
+            return res;
+        }
+        public bool Within(long num) {
+            return (num >= start && num <= end);
+        }
+        public long GetCount() {
+            return end - start;
+        }
+    }
+}
diff --git a/UI/TASFlow.xaml b/UI/TASFlow.xaml
index a8f7a5e..eb5ca4b 100644
--- a/UI/TASFlow.xaml
+++ b/UI/TASFlow.xaml
@@ -38,19 +38,20 @@
             <RowDefinition Height="auto"/>
             <RowDefinition Height="auto"/>
             <RowDefinition Height="auto"/>
+            <RowDefinition Height="auto"/>
             <RowDefinition Height="*"/>
         </Grid.RowDefinitions>
 
-        <TextBlock Padding="2" Background="#afafaf" Grid.Column="0" Grid.Row="0" Text="Frame"/>
-        <TextBlock Padding="2" Background="#afafaf" Grid.Column="0" Grid.Row="1" Text="Delta Time"/>
-        <TextBlock Padding="2" Background="#afafaf" Grid.Column="0" Grid.Row="2" Text="^"/>
-        <TextBlock Padding="2" Background="#afafaf" Grid.Column="0" Grid.Row="3" Text="v"/>
-        <TextBlock Padding="2" Background="#afafaf" Grid.Column="0" Grid.Row="4" Text="&lt;"/>
-        <TextBlock Padding="2" Background="#afafaf" Grid.Column="0" Grid.Row="5" Text="&gt;"/>
-        <TextBlock Padding="2" Background="#afafaf" Grid.Column="0" Grid.Row="6" Text="shift"/>
-        <TextBlock Padding="2" Background="#afafaf" Grid.Column="0" Grid.Row="7" Text="space"/>
-        <TextBlock Padding="2" Background="#afafaf" Grid.Column="0" Grid.Row="8" Text="q"/>
-        <TextBlock Padding="2" Background="#afafaf" Grid.Column="0" Grid.Row="9" Text="esc"/>
-        <TextBlock Padding="2" Background="#afafaf" Grid.Column="0" Grid.Row="10" Text="enter"/>
+        <TextBlock Padding="2" Background="#afafaf" Grid.Column="0" Grid.Row="1" Text="Frame"/>
+        <TextBlock Padding="2" Background="#afafaf" Grid.Column="0" Grid.Row="2" Text="Delta Time"/>
+        <TextBlock Padding="2" Background="#afafaf" Grid.Column="0" Grid.Row="3" Text="^"/>
+        <TextBlock Padding="2" Background="#afafaf" Grid.Column="0" Grid.Row="4" Text="v"/>
+        <TextBlock Padding="2" Background="#afafaf" Grid.Column="0" Grid.Row="5" Text="&lt;"/>
+        <TextBlock Padding="2" Background="#afafaf" Grid.Column="0" Grid.Row="6" Text="&gt;"/>
+        <TextBlock Padding="2" Background="#afafaf" Grid.Column="0" Grid.Row="7" Text="shift"/>
+        <TextBlock Padding="2" Background="#afafaf" Grid.Column="0" Grid.Row="8" Text="space"/>
+        <TextBlock Padding="2" Background="#afafaf" Grid.Column="0" Grid.Row="9" Text="q"/>
+        <TextBlock Padding="2" Background="#afafaf" Grid.Column="0" Grid.Row="10" Text="esc"/>
+        <TextBlock Padding="2" Background="#afafaf" Grid.Column="0" Grid.Row="11" Text="enter"/>
     </Grid>
 </UserControl>
diff --git a/UI/TASFlow.xaml.cs b/UI/TASFlow.xaml.cs
index 56e366e..dac2f19 100644
--- a/UI/TASFlow.xaml.cs
+++ b/UI/TASFlow.xaml.cs
@@ -21,12 +21,15 @@ namespace BallanceTASEditor.UI {
         public TASFlow() {
             InitializeComponent();
             mItemList = new List<TASFlowUIItem>();
+            mRectMap = new Dictionary<Rectangle, CellPosition>();
             mItemCount = 0;
             SetItemCount(1);
         }
 
         private int mItemCount;
         private List<TASFlowUIItem> mItemList;
+        private Dictionary<Rectangle, CellPosition> mRectMap;
+        public SelectionHelp SelectionHelp { get; set; }
         public List<FrameDataDisplay> DataSources { get; set; }
 
         public void RefreshDataSources() {
@@ -57,12 +60,12 @@ namespace BallanceTASEditor.UI {
             if (offset > 0) {
                 for (int i = 0; i < abs; i++) {
                     var newItem = new TASFlowUIItem(mItemCount + 1 + i);    // the first col is sheet header, so add 1 additionally
-                    newItem.Add(uiCoreWindow);
+                    newItem.Add(uiCoreWindow, mRectMap, Rectangle_MouseDown);
                     mItemList.Add(newItem);
                 }
             } else {
                 for(int i = 0; i < abs; i++) {
-                    mItemList[mItemCount].Remove(uiCoreWindow);
+                    mItemList[newCount + i].Remove(uiCoreWindow, mRectMap, Rectangle_MouseDown);
                 }
                 mItemList.RemoveRange(newCount, abs);
             }
@@ -71,57 +74,161 @@ namespace BallanceTASEditor.UI {
             mItemCount = newCount;
         }
 
+        public void RefreshDataMenu() {
+            if (SelectionHelp == null) return;
+
+            ToolMode mode = SelectionHelp.GetToolMode();
+            bool showCursorPasteAdd = mode == ToolMode.Cursor && SelectionHelp.IsDataPartialReady();
+            bool showFill = mode == ToolMode.Fill && SelectionHelp.IsDataReady();
+            bool showCursorCopyDelete = mode == ToolMode.Cursor && SelectionHelp.IsDataReady();
+
+            uiDataMenu_Set.IsEnabled = showFill;
+            uiDataMenu_Unset.IsEnabled = showFill;
+            uiDataMenu_Copy.IsEnabled = showCursorCopyDelete;
+            uiDataMenu_Delete.IsEnabled = showCursorCopyDelete;
+            uiDataMenu_PasteAfter.IsEnabled = showCursorPasteAdd;
+            uiDataMenu_PasteBefore.IsEnabled = showCursorPasteAdd;
+            uiDataMenu_AddAfter.IsEnabled = showCursorPasteAdd;
+            uiDataMenu_AddBefore.IsEnabled = showCursorPasteAdd;
+        }
+
+        public void RefreshSelectionHighlight() {
+            ToolMode mode = SelectionHelp.GetToolMode();
+
+            if (mode == ToolMode.Cursor) {
+                if (SelectionHelp.IsDataReady()) {
+                    var data = SelectionHelp.GetRange();
+                    foreach (var item in mItemList) {
+                        if (data.Within(item.rawFrame)) {
+                            item.SelectFull();
+                        } else {
+                            item.Unselect();
+                        }
+                    }
+                    return;
+                } else if (SelectionHelp.IsDataPartialReady()) {
+                    var data = SelectionHelp.GetPoint();
+                    foreach (var item in mItemList) {
+                        if (data == item.rawFrame) {
+                            item.SelectFull();
+                        } else {
+                            item.Unselect();
+                        }
+                    }
+                    return;
+                }
+            } else if (mode == ToolMode.Fill) {
+                if (SelectionHelp.IsDataReady()) {
+                    var data = SelectionHelp.GetRange();
+                    var field = SelectionHelp.GetFieldRange();
+                    foreach (var item in mItemList) {
+                        if (data.Within(item.rawFrame)) {
+                            item.SelectField(field);
+                        } else {
+                            item.Unselect();
+                        }
+                    }
+                    return;
+                }
+            }
+
+            // fail if prog run into this position, clear
+            foreach (var item in mItemList) {
+                item.Unselect();
+            }
+        }
+
+        private void Rectangle_MouseDown(object sender, MouseButtonEventArgs e) {
+            if (SelectionHelp == null) return;
+
+            // because the first column is header
+            // so all pos.column should -1
+            var rect = sender as Rectangle;
+            var pos = mRectMap[rect];
+            if (!mItemList[pos.column - 1].rawIsEnable) return;
+            if (e.MouseDevice.LeftButton == MouseButtonState.Pressed) {
+                SelectionHelp.FirstClick(mItemList[pos.column - 1].rawFrame, pos.field);
+            } else if (e.MouseDevice.RightButton == MouseButtonState.Pressed) {
+                SelectionHelp.LastClick(mItemList[pos.column - 1].rawFrame, pos.field);
+            }
+        }
+
     }
 
     public class TASFlowUIItem {
         private static readonly Thickness DEFAULT_MARGIN = new Thickness(2);
         private static readonly Thickness RECT_MARGIN = new Thickness(1);
-        private static readonly SolidColorBrush RECT_STROKE = new SolidColorBrush(Colors.Gray);
+        private static readonly SolidColorBrush SEL_RECT_NORMAL_BRUSH = new SolidColorBrush(Colors.White);
+        private static readonly SolidColorBrush SEL_RECT_SELECTED_BRUSH = new SolidColorBrush(Colors.Orange);
+        private static readonly SolidColorBrush SEL_RECT_STROKE = new SolidColorBrush(Colors.Gray);
         private static readonly Color COLOR_SET = Color.FromRgb(30, 144, 255);
         private static readonly Color COLOR_UNSET = Color.FromArgb(0, 255, 255, 255);
+        private static readonly Color COLOR_SELECTED = Colors.Orange;
+        private static readonly Color COLOR_UNSELECTED = Colors.Gray;
         private const int KEY_COUNT = 9;
+        private const double SELECTION_HEADER_HEIGHT = 10.0f;
 
         public TASFlowUIItem(int column) {
             // basic item
+            sel_rect = new Rectangle();
             frame = new TextBlock();
             deltaTime = new TextBlock();
 
-            Grid.SetRow(frame, 0);
-            Grid.SetRow(deltaTime, 1);
+            Grid.SetRow(sel_rect, 0);
+            Grid.SetRow(frame, 1);
+            Grid.SetRow(deltaTime, 2);
+            Grid.SetColumn(sel_rect, column);
             Grid.SetColumn(frame, column);
             Grid.SetColumn(deltaTime, column);
 
+            sel_rect.Margin = RECT_MARGIN;
             frame.Margin = DEFAULT_MARGIN;
             deltaTime.Margin = DEFAULT_MARGIN;
 
+            sel_rect.StrokeThickness = 3;
+            sel_rect.Stroke = SEL_RECT_STROKE;
+            sel_rect.Height = SELECTION_HEADER_HEIGHT;
+
             // keystates item
             keystates = new Rectangle[KEY_COUNT];
             keystatesFill = new SolidColorBrush[KEY_COUNT];
+            keystatesStroke = new SolidColorBrush[KEY_COUNT];
             for (int i = 0; i < KEY_COUNT; i++) {
                 keystates[i] = new Rectangle();
                 keystatesFill[i] = new SolidColorBrush(COLOR_UNSET);
-                Grid.SetRow(keystates[i], 2 + i);
+                keystatesStroke[i] = new SolidColorBrush(COLOR_UNSELECTED);
+                Grid.SetRow(keystates[i], 3 + i);
                 Grid.SetColumn(keystates[i], column);
                 keystates[i].Margin = RECT_MARGIN;
-                keystates[i].StrokeThickness = 1;
-                keystates[i].Stroke = RECT_STROKE;
+                keystates[i].StrokeThickness = 3;
+                keystates[i].Stroke = keystatesStroke[i];
                 keystates[i].Fill = keystatesFill[i];
             }
+
+            this.column = column;
+            rawFrame = 0;
+            rawIsEnable = false;
         }
 
-        public void Add(Grid target) {
+        public void Add(Grid target, Dictionary<Rectangle, CellPosition> map, MouseButtonEventHandler func) {
+            target.Children.Add(sel_rect);
             target.Children.Add(frame);
             target.Children.Add(deltaTime);
             for (int i = 0; i < KEY_COUNT; i++) {
                 target.Children.Add(keystates[i]);
+                keystates[i].MouseDown += func;
+                map.Add(keystates[i], new CellPosition(column, (FrameDataField)i));
             }
         }
 
-        public void Remove(Grid target) {
+        public void Remove(Grid target, Dictionary<Rectangle, CellPosition> map, MouseButtonEventHandler func) {
+            target.Children.Remove(sel_rect);
             target.Children.Remove(frame);
             target.Children.Remove(deltaTime);
             for (int i = 0; i < KEY_COUNT; i++) {
                 target.Children.Remove(keystates[i]);
+                keystates[i].MouseDown -= func;
+                map.Remove(keystates[i]);
             }
         }
 
@@ -144,11 +251,37 @@ namespace BallanceTASEditor.UI {
             for (int i = 0; i < KEY_COUNT; i++) {
                 keystates[i].Visibility = isEnable ? Visibility.Visible : Visibility.Collapsed;
             }
+
+            rawIsEnable = isEnable;
+            rawFrame = fdd.index;
         }
 
+        public void SelectFull() {
+            sel_rect.Fill = SEL_RECT_SELECTED_BRUSH;
+        }
+
+        public void SelectField(SelectionRange range) {
+            for (int i = 0; i < KEY_COUNT; i++) {
+                keystatesStroke[i].Color = range.Within(i) ? COLOR_SELECTED : COLOR_UNSELECTED;
+            }
+        }
+
+        public void Unselect() {
+            sel_rect.Fill = SEL_RECT_NORMAL_BRUSH;
+            for (int i = 0; i < KEY_COUNT; i++) {
+                keystatesStroke[i].Color = COLOR_UNSELECTED;
+            }
+        }
+
+        public long rawFrame;
+        public bool rawIsEnable;
+
+        public Rectangle sel_rect;
         public TextBlock frame;
         public TextBlock deltaTime;
         public Rectangle[] keystates;
         private SolidColorBrush[] keystatesFill;
+        private SolidColorBrush[] keystatesStroke;
+        private int column;
     }
 }
diff --git a/UI/TASViewer.cs b/UI/TASViewer.cs
index 5e1c642..96c4994 100644
--- a/UI/TASViewer.cs
+++ b/UI/TASViewer.cs
@@ -10,30 +10,35 @@ using System.Windows;
 
 namespace BallanceTASEditor.UI {
     public class TASViewer : IDisposable {
-        public TASViewer(TASFile file, Slider slider, TASFlow datagrid) {
+        public TASViewer(TASFile file, Slider slider, TASFlow datagrid, TextBlock statusbar) {
             mFile = file;
             mSlider = slider;
             mDataGrid = datagrid;
+            mStatusbar = statusbar;
 
             // restore slider
             mSlider.Minimum = 0;
             updateSliderRange();
 
+            // init selection
+            mSelectionHelp = new SelectionHelp();
+            mSelectionHelp.SelectionChanged += funcSelectionHelp_SelectionChanged;
+
             // init data
             mPosition = 0;
-            mDataSource = new List<FrameDataDisplay>();
             INVALID_FRAME_DATA = new FrameData(-1f, 0);
-            for (int i = 0; i < DATA_LIST_LENGTH; i++) {
-                mDataSource.Add(new FrameDataDisplay(0, INVALID_FRAME_DATA));
-            }
-            mFile.Get(mDataSource, 0, DATA_LIST_LENGTH);
+            mDataSource = new List<FrameDataDisplay>();
+            mListLength = 0;
 
             // bind event and source
-            mDataGrid.SetItemCount(DATA_LIST_LENGTH);
             mDataGrid.DataSources = mDataSource;
-            mDataGrid.RefreshDataSources();
+            mDataGrid.SelectionHelp = mSelectionHelp;
             mSlider.ValueChanged += sliderValueChanged;
+
+            // display data
+            ChangeListLength(DATA_LIST_LENGTH);
         }
+
         public void Dispose() {
             mDataGrid.DataSources = null;
             mSlider.ValueChanged -= sliderValueChanged;
@@ -43,18 +48,20 @@ namespace BallanceTASEditor.UI {
         FrameData INVALID_FRAME_DATA;
         TASFile mFile;
         Slider mSlider;
+        TextBlock mStatusbar;
         TASFlow mDataGrid;
+        SelectionHelp mSelectionHelp;
         long mPosition;
+        int mListLength;
         List<FrameDataDisplay> mDataSource;
 
         private void sliderValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e) {
             long pos = Convert.ToInt64(Math.Floor(e.NewValue));
             long offset = pos - mPosition;
             mFile.Shift(offset);
-            mFile.Get(mDataSource, pos, DATA_LIST_LENGTH);
 
+            RefreshDisplay(pos);
             mPosition = pos;
-            mDataGrid.RefreshDataSources();
         }
 
         private void updateSliderRange() {
@@ -63,5 +70,76 @@ namespace BallanceTASEditor.UI {
                 mSlider.Value = newSize;
             mSlider.Maximum = newSize;
         }
+
+        private void funcSelectionHelp_SelectionChanged() {
+            mDataGrid.RefreshDataMenu();
+            mDataGrid.RefreshSelectionHighlight();
+            OnStatusbarSelectionChanged();
+        }
+
+        private void OnStatusbarSelectionChanged() {
+            var mode = mSelectionHelp.GetToolMode();
+
+            switch (mode) {
+                case ToolMode.Cursor:
+                    if (mSelectionHelp.IsDataReady()) {
+                        var data = mSelectionHelp.GetRange();
+                        mStatusbar.Text = $"{data.start} - {data.end}";
+                    } else if (mSelectionHelp.IsDataPartialReady()) {
+                        var data2 = mSelectionHelp.GetPoint();
+                        mStatusbar.Text = data2.ToString();
+                    } else mStatusbar.Text = "-";
+                    break;
+                case ToolMode.Fill:
+                    if (mSelectionHelp.IsDataReady()) {
+                        var data3 = mSelectionHelp.GetRange();
+                        mStatusbar.Text = $"{data3.start} - {data3.end}";
+                    } else mStatusbar.Text = "-";
+                    break;
+                case ToolMode.Overwrite:
+                    if (mSelectionHelp.IsDataReady()) {
+                        var data4 = mSelectionHelp.GetPoint();
+                        mStatusbar.Text = data4.ToString();
+                    } else mStatusbar.Text = "-";
+                    break;
+            }
+        }
+
+        public void ChangeListLength(int newLen) {
+            if (newLen < 5 || newLen > 30) return;
+            int offset = newLen - mListLength;
+            int abs = Math.Abs(offset);
+            if (offset == 0) return;
+
+            // change mDataSource first
+
+            if (offset > 0) {
+                for (int i = 0; i < abs; i++) {
+                    mDataSource.Add(new FrameDataDisplay(0, INVALID_FRAME_DATA));
+                }
+            } else {
+                mDataSource.RemoveRange(newLen, abs);
+            }
+
+            // then change viewer control
+            mDataGrid.SetItemCount(newLen);
+
+            // apply new value
+            mListLength = newLen;
+
+            // then refresh
+            RefreshDisplay(mPosition);
+        }
+
+        public void RefreshDisplay(long pos) {
+            mFile.Get(mDataSource, pos, mListLength);
+            mDataGrid.RefreshDataSources();
+            mDataGrid.RefreshSelectionHighlight();
+        }
+    
+        public void ChangeToolMode(ToolMode mode) {
+            mSelectionHelp.SetMode(mode);
+        }
+
     }
 }
diff --git a/UI/Util.cs b/UI/Util.cs
new file mode 100644
index 0000000..ca2aab7
--- /dev/null
+++ b/UI/Util.cs
@@ -0,0 +1,24 @@
+using BallanceTASEditor.Core.TASStruct;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace BallanceTASEditor.UI {
+
+
+    public enum ToolMode {
+        Cursor,
+        Fill,
+        Overwrite
+    }
+
+    public struct CellPosition {
+        public CellPosition(int column, FrameDataField field) {
+            this.column = column;
+            this.field = field;
+        }
+        public int column;
+        public FrameDataField field;
+    }
+}