985360: Updated ReadMe file

README.md

@@ -1,2 +1,95 @@
-# How-to-programmatically-select-all-DropDownItems-in-SfComboBox
-This repository contains the sample that how to programmatically select all DropDownItems in SfComboBox
+# How to Programmatically Select All DropDown Items in WinForms SfComboBox
+This example demonstrates how to programmatically select all items in the Syncfusion WinForms SfComboBox control. The SfComboBox supports advanced features like multi-selection, auto-complete, and data binding. Selecting all items programmatically is useful for scenarios such as applying bulk actions or initializing default selections.
+
+## Why This Is Useful
+- **Batch Operations**: Apply global settings to all items.
+- **Default Selections**: Pre-select all items when loading data.
+- **Improved UX**: Avoid manual selection for large lists.
+
+## Key Steps
+- Set _ComboBoxMode_ to MultiSelection to allow multiple selections.
+- Bind the data source to the SfComboBox.
+- Iterate through all items and add them to _CheckedItems_ collection.
+- Refresh the UI to reflect the changes.
+
+## Code example
+
+**Designer**
+```C#
+#region Windows Form Designer generated code
+private void InitializeComponent()
+{
+    this.sfComboBox1 = new Syncfusion.WinForms.ListView.SfComboBox();
+    this.button1 = new System.Windows.Forms.Button();
+    ((System.ComponentModel.ISupportInitialize)(this.sfComboBox1)).BeginInit();
+    this.SuspendLayout();
+
+    // sfComboBox1
+    this.sfComboBox1.Location = new System.Drawing.Point(445, 143);
+    this.sfComboBox1.Name = "sfComboBox1";
+    this.sfComboBox1.Size = new System.Drawing.Size(257, 57);
+    this.sfComboBox1.TabIndex = 0;
+
+    // button1
+    this.button1.Location = new System.Drawing.Point(33, 162);
+    this.button1.Name = "button1";
+    this.button1.Size = new System.Drawing.Size(211, 38);
+    this.button1.Text = "Select Programmatically";
+    this.button1.Click += new System.EventHandler(this.button1_Click);
+
+    // Form1
+    this.ClientSize = new System.Drawing.Size(800, 450);
+    this.Controls.Add(this.button1);
+    this.Controls.Add(this.sfComboBox1);
+    this.Text = "SfComboBox_CheckedItems";
+
+    ((System.ComponentModel.ISupportInitialize)(this.sfComboBox1)).EndInit();
+    this.ResumeLayout(false);
+}
+#endregion
+```
+
+**Logic**
+```C#
+
+public Form1()
+{
+    InitializeComponent();
+
+    // Bind data source
+    sfComboBox1.DataSource = GetTable();
+    sfComboBox1.DisplayMember = "Patient";
+    sfComboBox1.ValueMember = "Drug";
+    sfComboBox1.ComboBoxMode = ComboBoxMode.MultiSelection;
+    this.StartPosition = FormStartPosition.CenterScreen;
+}
+
+private static DataTable GetTable()
+{
+    DataTable table = new DataTable();
+    table.Columns.Add("Dosage", typeof(int));
+    table.Columns.Add("Drug", typeof(string));
+    table.Columns.Add("Patient", typeof(string));
+    table.Columns.Add("Date", typeof(DateTime));
+
+    table.Rows.Add(25, "Indocin", "David", DateTime.Now);
+    table.Rows.Add(50, "Enebrel", "Sam", DateTime.Now);
+    table.Rows.Add(10, "Hydralazine", "Christoff", DateTime.Now);
+    table.Rows.Add(21, "Combivent", "Janet", DateTime.Now);
+    table.Rows.Add(100, "Dilantin", "Melanie", DateTime.Now);
+    return table;
+}
+
+private void button1_Click(object sender, EventArgs e)
+{
+    foreach (var item in sfComboBox1.DropDownListView.View.Items.ToList())
+    {
+        sfComboBox1.DropDownListView.CheckedItems.Add(item);
+    }
+}
+```
+
+## Notes
+- Ensure ComboBoxMode is set to MultiSelection for multiple selections.
+- Use CheckedItems collection to programmatically select items.
+- This approach works for both static and dynamic data sources.