Question

A user is not allowed to resize a TextBox control vertically. The height of a TextBox is locked to the ideal height that a textbox should be.

What’s more, Visual Studio doesn’t even provide you vertical drag handles:

How do i provide the same mechanism on my UserControl?

Answer 1

I will elaborate on Hans’ comment. You can associate specialized code (called a Designer) with a UserControl so that when it is placed on a form in Visual Studio, the user is limited in how they can configure your control.

1. Add a reference to System.Design in your project.

2. Use the following sample code:

   [Designer(typeof(FixedHeightUserControlDesigner))]
   public partial class FixedHeightUserControl : UserControl
   {
       private const int FIXED_HEIGHT = 25;
   
       protected override void OnSizeChanged(EventArgs e)
       {
           if (this.Size.Height != FIXED_HEIGHT)
               this.Size = new Size(this.Size.Width, FIXED_HEIGHT);
   
           base.OnSizeChanged(e);
       }
   
       public FixedHeightUserControl()
       {
           InitializeComponent();
   
           this.Height = FIXED_HEIGHT;
       }
   }
   
   public class FixedHeightUserControlDesigner : ParentControlDesigner
   {
       private static string[] _propsToRemove = new string[] { "Height", "Size" };
   
       public override SelectionRules SelectionRules
       {
           get { return SelectionRules.LeftSizeable | SelectionRules.RightSizeable | SelectionRules.Moveable; }
       }
   
       protected override void PreFilterProperties(System.Collections.IDictionary properties)
       {
           base.PreFilterProperties(properties);
           foreach (string p in _propsToRemove)
               if (properties.Contains(p))
                   properties.Remove(p);
       }
   }