How to Disable Default Pushbutton Handling for MFC Dialog

Windows dialog boxes support the use of a default button (pushbutton) that is automatically activated when the ENTER key is pressed while focus is not on a command button. The MFC class library will automatically call the CDialog::OnOK() virtual function for a dialog whenever the default button (pushbutton) is activated by pressing the ENTER key.

This behavior conforms to the guidelines set forth by "The Windows Interface: An Application Design Guide." This manual is included with the Windows version 3.1 SDK documentation. It is also available from Microsoft Press.

Although default button (pushbutton) support is recommended, you might want to disable or modify the standard implementation in certain situations. You can do this in an MFC application by following these steps:

1. Load the dialog into App Studio and change the OK button identifier from IDOK to something else such as IDC_MYOK. Also, clear the check from Default Button property.
2. Use ClassWizard to create a message handling function for this button named OnClickedMyOK. This function will be executed when a BN_CLICKED message is received from this button.
3. In the code for OnClickedMyOK, call the base class version of the OnOK function. Here is an example:

      void CMyDialog::OnClickedMyOK()
      {
         CDialog::OnOK();
      }
   						

4. Override OnOK for your dialog, and do nothing inside the function. Here is an example:

      void CMyDialog::OnOK()
      {
      }
   						

5. Run the program and bring up the dialog. Give focus to a control other than the OK button. Press the RETURN key. Notice that CDialog::OnOK() is never executed.

This technique effectively disables the standard default button (pushbutton) support in an MFC program. The OK button will continue to behave as before when activated by the mouse or through a mnemonic keystroke, but the ENTER key will not trigger OnOK handling.

This same technique can be used to disable or modify default OnCancel processing. The escape key generates a call to CDialog::OnCancel just as the enter key generates an OnOK function call.