comboBox1.Focus();
private void Form1_Load(object sender, EventArgs e) { comboBox1.Items.Add("Option 1"); comboBox1.Items.Add("Option 2"); comboBox1.Items.Add("Option 3"); comboBox1.SelectedIndex = 0; // Select the first item comboBox1.Focus(); }In this example, the ComboBox control is populated with three options using the Items property and the SelectedIndex property is set to 0 so that the first option is selected by default. The Focus method is then called to set the input focus to the control. The package library for System.Windows.Forms.ComboBox is the Windows Forms library, which is part of the .NET Framework and can be used in Visual Studio to create Windows desktop applications with a graphical user interface.