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Merge pull request #720 from telerik/dkrastev/m-KB
KB-ChartView closest data point
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‎knowledge-base/chartview-scatterseries-closest-point-mouseclick.md‎

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---
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title: Finding the Nearest ScatterDataPoint to a Mouse Click in RadChartView
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description: Learn how to determine the closest ScatterDataPoint in a RadChartView when the user clicks within the chart area.
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type: how-to
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page_title: How to Identify the Closest ScatterDataPoint to a Mouse Click in RadChartView
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slug: chartview-scatterseries-closest-point-mouseclick
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tags: radchartview, scatterdatapoint, winforms, mouseeventargs, chart-axes
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res_type: kb
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ticketid: 1686235
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---
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## Environment
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|Product Version|Product|Author|
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|----|----|----|
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|2025.1.211|RadChartView for WinForms|[Dinko Krastev](https://www.telerik.com/blogs/author/dinko-krastev)|
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## Description
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This article will demonstrate how to determine the nearest ScatterDataPoint to a mouse click location using the mouse click position.
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![WinForms RadChartView ClosestDataPoint](images/chartView-closestdatapoint.png)
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## Solution
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To achieve this, calculate the axis values corresponding to the mouse click position on the chart. Then iterate over the data points in the series and determine the closest one.
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Once the closest point is identified, you can create an additional ScatterSeries and add a duplicate ScatterDataPoint with the same values. This secondary series can be used to visually highlight the nearest data point.
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The following code snippet demonstrates a full implementation.
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````C#
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public partial class Form1 : Form
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{
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ScatterSeries scatterSeries = new ScatterSeries();
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public Form1()
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{
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InitializeComponent();
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scatterSeries.Name = "";
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scatterSeries.DataPoints.Add(new ScatterDataPoint(19000, 15));
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scatterSeries.DataPoints.Add(new ScatterDataPoint(10000, 18));
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scatterSeries.DataPoints.Add(new ScatterDataPoint(15000, 13));
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scatterSeries.DataPoints.Add(new ScatterDataPoint(80000, 10));
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scatterSeries.DataPoints.Add(new ScatterDataPoint(60000, 25));
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scatterSeries.PointSize = new SizeF(5, 5);
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this.radChartView1.Series.Add(scatterSeries);
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this.radChartView1.MouseDown += RadChartView1_MouseDown;
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}
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private void RadChartView1_MouseDown(object sender, MouseEventArgs e)
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{
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Point pt = this.radChartView1.ChartElement.Wrapper.PointFromControl(e.Location);
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double verticalValue = Convert.ToDouble(GetVerticalAxisValueFromMouse(e));
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double horizontalValue = Convert.ToDouble(GetHorizontalAxisValueFromMouse(e));
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Debug.WriteLine("X: " + horizontalValue + " Y: " + verticalValue);
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ScatterDataPoint closestPoint = null;
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double minDistance = double.MaxValue;
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var seriesToRemove = this.radChartView1.Series.FirstOrDefault(s => s.Name =="Closest Point");
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if (seriesToRemove != null)
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{
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this.radChartView1.Series.Remove(seriesToRemove);
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}
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foreach (ScatterDataPoint dataPoint in scatterSeries.DataPoints)
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{
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// Calculate the Euclidean distance
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double distance = Math.Sqrt(Math.Pow(dataPoint.XValue - horizontalValue, 2) + Math.Pow((double)dataPoint.YValue - verticalValue, 2));
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// Update the closest point if the current distance is smaller
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if (distance < minDistance)
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{
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minDistance = distance;
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closestPoint = dataPoint;
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}
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}
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if (closestPoint != null)
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{
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var newScatterSeries = new ScatterSeries();
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newScatterSeries.Name = "Closest Point";
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newScatterSeries.DataPoints.Add(new ScatterDataPoint(closestPoint.XValue, (double)closestPoint.YValue));
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newScatterSeries.PointSize = new SizeF(15, 15);
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newScatterSeries.BorderColor = Color.Red;
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this.radChartView1.Series.Add(newScatterSeries);
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this.radChartView1.Invalidate();
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this.radChartView1.Update();
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}
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}
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private object GetHorizontalAxisValueFromMouse(MouseEventArgs e)
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{
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LinearAxis axis = radChartView1.Axes[0] as LinearAxis;
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IChartView view = (IChartView)axis.View;
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double delta = axis.ActualRange.Maximum - axis.ActualRange.Minimum;
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double totalWidth = axis.Model.LayoutSlot.Width;
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double ratio = 1 - (e.Location.X - this.radChartView1.Area.View.Viewport.X - view.PlotOriginX - axis.Model.LayoutSlot.X) / (totalWidth * view.ZoomWidth);
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double value = axis.ActualRange.Minimum + delta * ratio;
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return axis.ActualRange.Maximum - value;
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}
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private object GetVerticalAxisValueFromMouse(MouseEventArgs e)
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{
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LinearAxis axis = radChartView1.Axes[1] as LinearAxis;
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IChartView view = (IChartView)axis.View;
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double delta = axis.ActualRange.Maximum - axis.ActualRange.Minimum;
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double totalHeight = axis.Model.LayoutSlot.Height;
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double ratio = 1 - (e.Location.Y - this.radChartView1.Area.View.Viewport.Y - view.PlotOriginY - axis.Model.LayoutSlot.Y) / (totalHeight * view.ZoomHeight);
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double value = axis.ActualRange.Minimum + delta * ratio;
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return value;
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}
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}
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````
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## See Also
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- [RadChartView Overview Documentation](https://docs.telerik.com/devtools/winforms/controls/chartview/overview)

‎knowledge-base/images/chartView-closestdatapoint.png‎

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‎knowledge-base/menu-highlight-last-click-item.md‎

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---
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title: Highlight the Last Selected Menu Item In RadMenu
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description: Learn how to keep selected menu items highlighted in RadMenu for WinForms by implementing custom code.
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type: how-to
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page_title: Highlighting Selected Menu Items in RadMenu for WinForms
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slug: menu-highlight-last-click-item
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tags: menus, winforms, menu-item, highlight
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res_type: kb
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ticketid: 1687046
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---
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## Environment
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|Product Version|Product|Author|
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|----|----|----|
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|2025.1.211|RadMenu for WinForms|[Dinko Krastev](https://www.telerik.com/blogs/author/dinko-krastev)|
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## Description
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A common requirement is to highlight the last selected RadMenuItem. This article will demonstrate how this can be achieved.
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## Solution
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RadMenu for WinForms does not support this behavior out of the box. To achieve it, use custom code to manage the highlighting of the menu items. Subscribe to the `Click` event of each `RadMenuItem` and implement logic to change the `BackColor` property of the clicked item while resetting the previous item's background.
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### Example Code
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Below is a code example demonstrating the custom solution:
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````C#
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public partial class Form2 : Form
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{
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public Form2()
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{
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InitializeComponent();
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DesertTheme desertTheme = new DesertTheme();
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ThemeResolutionService.ApplicationThemeName = desertTheme.ThemeName;
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foreach (RadMenuItem item in this.radMenu1.Items)
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{
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item.Click += RadMenuItem_Click;
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foreach (RadMenuItem subItem in item.Items)
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{
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subItem.Click += RadMenuItem_Click;
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}
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}
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}
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RadMenuItem lastSelectedMenuItem = null;
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RadMenuItem lastSelectedSubMenuItem = null;
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void ResetColor(RadMenuItem radMenuItem)
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{
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if (radMenuItem != null)
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{
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radMenuItem.FillPrimitive.BackColor = Color.Transparent;
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radMenuItem.FillPrimitive.GradientStyle = GradientStyles.Linear;
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}
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}
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void ResetColor(RadMenuItem radMenuItem)
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{
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if (radMenuItem != null)
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{
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radMenuItem.FillPrimitive.ResetValue(Telerik.WinControls.Primitives.FillPrimitive.BackColorProperty, Telerik.WinControls.ValueResetFlags.Local);
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radMenuItem.FillPrimitive.ResetValue(Telerik.WinControls.Primitives.FillPrimitive.GradientStyleProperty, Telerik.WinControls.ValueResetFlags.Local);
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}
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}
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private void RadMenuItem_Click(object sender, EventArgs e)
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{
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var newSelectedMenuItem = sender as RadMenuItem;
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if (newSelectedMenuItem != null)
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{
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if (lastSelectedMenuItem == null)
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{
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lastSelectedMenuItem = newSelectedMenuItem;
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ChangeColor(lastSelectedMenuItem);
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}
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else
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{
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var text1 = this.lastSelectedMenuItem.Text;
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var text2 = newSelectedMenuItem.Text;
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if (newSelectedMenuItem.HierarchyParent is RadMenuItem parentMenuItem)
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{
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if (lastSelectedSubMenuItem != newSelectedMenuItem)
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{
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ResetColor(lastSelectedSubMenuItem);
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}
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lastSelectedSubMenuItem = newSelectedMenuItem;
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ChangeColor(lastSelectedSubMenuItem);
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if (lastSelectedMenuItem != null)
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{
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ResetColor(lastSelectedMenuItem);
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}
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lastSelectedMenuItem = parentMenuItem;
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ChangeColor(parentMenuItem);
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}
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else
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{
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if (lastSelectedMenuItem == newSelectedMenuItem)
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{
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return;
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}
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if (lastSelectedSubMenuItem != null)
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{
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ResetColor(lastSelectedSubMenuItem);
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}
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ResetColor(lastSelectedMenuItem);
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lastSelectedMenuItem = newSelectedMenuItem;
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ChangeColor(newSelectedMenuItem);
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}
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}
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}
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}
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}
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````
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### Notes
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- The code supports one level of subitems. For deeper hierarchies, extend the logic to support multiple levels of hierarchy.
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## See Also
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- [RadMenu Documentation](https://docs.telerik.com/devtools/winforms/controls/menus/menu/overview)

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