Creating an Extended Combo Box Control
How the extended combo box control is created depends on whether you are using the control in a dialog box or creating it in a nondialog window.
To use CComboBoxEx directly in a dialog box
In the dialog editor, add an Extended Combo Box control to your dialog template resource. Specify its control ID.
Specify any styles required, using the Properties dialog box of the extended combo box control.
Use ClassWizard to add a member variable of type with the Control property. You can use this member to call CComboBoxEx member functions.
Use ClassWizard to map handler functions in the dialog class for any extended combo box control notification messages you need to handle.
To use CComboBoxEx in a nondialog window