如何从“工具箱”中隐藏一个额外的控件？

Question

Creating a library with new controls. It has 2 classes "HandySeparator - Basic" and "HandyHSeparator - Derived". The base class inherits the Control class. It contains properties that call the Invalidate() method. In the derived class, inside the OnPaint() method, the element is being drawn.

The catch is that after rebuilding the library, a control with the name of the base class appears in the "Toolbox", but I don't need it there.

** HandySeparator **

  public class HandySeparator : Control {
    private DashStyle dashStyle;
    public DashStyle DashStyle {
      get { return dashStyle; }
      set {
        dashStyle = value;
        Invalidate ();
      }
    }

  ...
  }

** HandyHSeparator **

  public class HandyHSeparator : HandySeparator {
  ...
  
  ... OnPaint(...) {
    /// Draw element
  }

  ...
  }

Answer 1

** HandySeparator **

  [ToolboxItem(false)]
  public class HandySeparator : Control {
    private DashStyle dashStyle;
    public DashStyle DashStyle {
      get { return dashStyle; }
      set {
        dashStyle = value;
        Invalidate ();
      }
    }

  ...
  }

** HandyHSeparator **

  [ToolboxItem(true)]
  public class HandyHSeparator : HandySeparator {
  ...
  
  ... OnPaint(...) {
    /// Draw element
  }

  ...
  }