Hi,

I am trying to launch our software application help file in VB6. Initially, we had generated a ".hlp" Help file. We tested it and it worked fine under Windows XP. However, Windows Vista no longer supports ".hlp" format Help file. So, we ended up compiling and generating a ".chm" HTML Help file.

Now we are running into a problem, which is that the HTML ".chm" Help format can be launched from a VB app. in Windows Vista, but not in Windows XP. Another strange thing is that in Windows XP, I can double click on the ".chm" Help file and it will launch and open. Also, from within my VB6 app, I can generate an error message box (MsgBox) and invoke help with a proper context ID and am able to launch the HTML ".chm" Help file. I'm wondering if this is because we are using an older Microsoft Common Dialog Control library in VB6. The version we are currently using is MS Common Dialog Control SP6. I tried searching the net last night, but could not find a link anywhere for a newer version.

Does anyone have any ideas or thoughts on this problem? We really appreciate any leads on this.

Thank you very much for all your help.

Khoi Nguyen

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Khoi Nguyen

Hi all,

I did some research and found the following solution that works great. For the whole time, I was stuck in thinking that it's the problem with the MS Common Dialog Control. Well, the answer is that if you want to launch an HTML ".chm" Help file from VB6, you would not use MS Common Dialog Control at all.

VB provides an API function called "HTMLHelp". To gain access to this function, you will need to provide the following declaration:

Private Declare Function HTMLHelp Lib "HHCtrl.ocx" Alias "HTMLHelpA" _
    (ByVal hWndCaller As Long, _
     ByVal pszFile As String, _
     ByVal uCommand As Long, _
     ByVal dwData As Long) As Long

To use it, try the following:

HtmlHelp hWnd, "HHDemo.chm", HH_HELP_CONTEXT, ByVal 100&

where the constants are defined as follows:

Const HH_DISPLAY_TOPIC As Long = 0
Const HH_HELP_CONTEXT As Long = &HF
Const HH_DISPLAY_TOC = &H1

For more information, you can reference Microsoft knowledge base Article 315988 thru the following link:

http://support.microsoft.com/kb/315988/en-us

Thanks to everyone for reading my post.

Have a nice day,

Khoi.

Khoi Nguyen