wait cursor comes but still i am able to click the button

Disabling the button is the only neat solution. However you have also two (ugly) alternatives:

• In the button click handler, if you are in 'wait cursor' state then do nothing.

or

• Make a owner drawn button, and represent the disabled state with the same image used for the active one.

It is possible to perform mouse operations even though it shows wait cursor.
So you have to handle the button click according to your situation.

A wait cursor may indicate a running process but still allow interaction. E. g. for some operations it might be desirable for the user to be able to cancel the operation, so the [cancel] button should still be active. Therefore changing your cursor to a wait cursor should not (and does not) block all input. It is your task to disable all components that the user should not interact with during processing.

A common method to prevent user interaction during a process is show a dialog using the DoModal() function and maybe show the progress of your operation on that dialog. The DoModal() function opens the dialog in modal mode, preventing all input to the rest of the application. You can then put a [cancel] button on that dialog if your users are allowed to do that, or buttons for any other interactions that you still allow, but anything else will be blocked.

Just construct an instance of CSafeWaitCursor
at the begining of your OnClick()-reaction :) :

class CYourApp : public CWinApp
{
  bool  m_bShielded;
  //...
public:
  //...
  void SetShielded(bool bSet) { m_bShielded = bSet; }
  bool IsShielded() const { return m_bShielded; }
};

/*virtual*/ BOOL CYourApp::PreTranslateMessage(MSG* pMsg)
{
  if (IsShielded()) {
    if ((pMsg->message >= WM_MOUSEFIRST && pMsg->message <= WM_MOUSELAST) ||
        (pMsg>= WM_KEYFIRST && pMsg->message <= WM_KEYLAST)) {
      return TRUE;
    }
  }
  return CWinApp::PreTranslateMessage(pMsg);
}

class CSafeWaitCursor
{
public:
  CSafeWaitCursor()
  {
    CYourApp* pcApp = (CYourApp*) AfxGetApp();
    pcApp->SetShielded(true);
    pcApp->DoWaitCursor(1);
  }
  ~CSafeWaitCursor()
  {
    CYourApp* pcApp = (CYourApp*) AfxGetApp();
    pcApp->SetShielded(false);
    pcApp->DoWaitCursor(-1);
  }
};

Problem : If your application consists of multiple buttons, disabling all the controls might not be good idea.

Temp Solution : We can create a new empty form with no borders, titles etc and having an opacity of 10-20% and then when wait cursor is getting called at the same time we can open this form.
We can close the form along with the wait cursor.