* Bound controls provide a way for user input. They differ from standard controls in their behavior.
  * As the user inputs data in a bound control it is automatically validated. 
  * If the data is correct it is put in the undo/redo mechanism.
  * If da data is correct the information in the bound control is sent to the bound data-holder(the control model).
  * This transition is two-way. 
  * They allow to attach a model and a verification mechanism. 
 * Bound controls are composed of:
  * a standard control
  * an icon. It shows the verification status. It can be either correct (a green tick) or incorrect (a red cross.)
  * a label (optionally). 
 * We need:
  * Some base bound control which eases bound controls creation
  * Text box
  * Drop-down list
  * Spinner
  * Check-box