<p>I want to create a subclass of TabPage that contains some control, and I want to control the layout and properties of those controls through the designer.  However, if I open my subclass in the designer, I can't position them like I could on a UserControl.  I don't want to have to create a TabPage with an UserControl instance on it, I want to design the TabPage directly.</p>

<p>How do I do that?  I've tried changing the Designer and DesignerCategory attributes, but I haven't found any values that help.</p>

I've had a similar problem in the past.
What i did first was switch from inheriting Usercontrol to tabpage like so
class UserInterface : UserControl // Do designer bit then change it to
class UserInterface : TabPage
Second i Just put all my controls and stuff in the usercontrol and docked that into a tabpage.
third i've made a generic class that takes any usercontrol and does the docking automatically.
so you can take your 'UserInterface' class and just get a type that you can add to a System.Windows.Forms.TabControl
```
```
public class UserTabControl<T> : TabPage
    where T : UserControl, new ()
{
    private T _userControl;
    public T UserControl 
    { 
        get{ return _userControl;}
        set
        {          
            _userControl = value;
            OnUserControlChanged(EventArgs.Empty);
        }
    }
    public event EventHandler UserControlChanged;
    protected virtual void OnUserControlChanged(EventArgs e)
    {
        //add user control docked to tabpage
        this.Controls.Clear();      
        UserControl.Dock = DockStyle.Fill;
        this.Controls.Add(UserControl);

        if (UserControlChanged != null)
        {
            UserControlChanged(this, e);
        }
    }

    public UserTabControl() : this("UserTabControl")
    {
    }

    public UserTabControl(string text) 
        : this( new T(),text )
    {
    }

    public UserTabControl(T userControl) 
        : this(userControl, userControl.Name)
    {
    }

    public UserTabControl(T userControl, string tabtext)
        : base(tabtext)
    {
        InitializeComponent();
        UserControl = userControl;  
    }

    private void InitializeComponent()
    {
        this.SuspendLayout();
        // 
        // UserTabControl
        // 

        this.BackColor = System.Drawing.Color.Transparent;
        this.Padding = new System.Windows.Forms.Padding(3);
        this.UseVisualStyleBackColor = true;
        this.ResumeLayout(false);
    }
}
```
```