The following example creates a PopupContainerControl with a RichTextBox inside, and assigns this control to a PopupContainerEdit editor.
RichTextBox rtb = new RichTextBox();
rtb.Dock = DockStyle.Fill;
PopupContainerControl popupControl = new PopupContainerControl();
popupControl.Controls.Add(rtb);
PopupContainerEdit editor = new PopupContainerEdit();
editor.Properties.PopupControl = popupControl;
Controls.Add(editor);
Dim rtb As RichTextBox = New RichTextBox
rtb.Dock = DockStyle.Fill
Dim popupControl As PopupContainerControl = New PopupContainerControl
popupControl.Controls.Add(rtb)
Dim editor As PopupContainerEdit = New PopupContainerEdit
editor.Properties.PopupControl = popupControl
Controls.Add(editor)