htmlhelp API pressing the cancel button

[softmessager]

Hi Forum

I have the following code ...

        hHtmlHelp = HtmlHelp( hWndHandle,
                              szHelpFileName,
                              uiHelpCommand, 
                              (DWORD)&link);
    if (hHtmlHelp==NULL) {
        MessageBox(hMainWnd,"Internal Help error"...... etc

This API displays the Topics found and then when I press the Display after selecting the topic. displays the HTML help for that topic

But
If I press Cancel on the "Topic Found" dialog box, then my program enters this if Condition..
I notice that even If I press CANCEL button, the 'hHtmlHelp' variable remains NULL.

Question :
How to detect if the user has pressed the cancel button instead of any other error ..

Thanks in Advance
Soft