About hidden components
Components can be used on a form and at the same time be set so that they are not visible (are "hidden") in Runtime Mode. You can also set them to be either visible or hidden, depending on certain conditions that you define.
Normally, these components are still visible in Deisng Mode. However, you can control whether you see hidden components in Design Mode with a setting in the User Preferences window. The option that controls this is Show Hidden Components, which is located on the Design Time tab.
Even when a component is hidden in Design Mode, you can locate and select the component using either the Object Viewer or the drop-down list of components at the top of the Component property sheet.