There is a control at the moment called CMS.Controls.ImageSelector. I can create a UserControl and in the code behind write the following code.

selector = new ImageSelector();
Controls.Add(selector);

This will allow me to select an image from the tree or from the media library.

That was an example.

What I need:
A similar control that would allow me to select a page from the tree. So I could.

selector = new PageSelector();
Controls.Add(selector);
button = new Button();
Controls.Add(button)

void button_click()
{
selectedPage = selector.value;
}

or something like that.

Hope thats clear