[Bug 39930] New: HtmlHelp() shows blank page when '\\' is used as path separator after '::'

https://bugs.winehq.org/show_bug.cgi?id=39930

Bug ID: 39930
           Summary: HtmlHelp() shows blank page when '\' is used as path
                    separator after '::'
           Product: Wine
           Version: 1.9.0
          Hardware: x86-64
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: hhctrl.ocx
          Assignee: [e-mail]
          Reporter: [e-mail]
      Distribution: ---

Despite the fact that Microsoft documentation clearly states that

Anything after the double colon (::) must use forward slashes (/),
    in accordance with URL standards.

(see https://support.microsoft.com/en-us/kb/235226), Windows developers tend to
forget(?) that rule and use backslashes () after the double colon.

For example, running UFile 2013 under Wine, opening the tutorial comes up with
a blank window, and the trace/fixme messages are logged:

trace:htmlhelp:HtmlHelpW (0x1006e,
L"ubxkbE.chm::\tutorial/pages/1intro.htm>DT_HTML_TUT",
command=HH_DISPLAY_TOPIC, data=0)
    trace:htmlhelp:NavigateToChm 0x208ba0 L"C:\Program Files\UFile
2013\ubxkbE.chm" L"\tutorial/pages/1intro.htm"
    trace:htmlhelp:AppendFullPathURL L"C:\Program Files\UFile
2013\ubxkbE.chm" 0x31dc98 L"\tutorial/pages/1intro.htm"
    trace:htmlhelp:navigate_url L"mk:@MSITStore:C:\Program Files\UFile
2013\ubxkbE.chm::/\tutorial/pages/1intro.htm"
    fixme:ieframe:handle_navigation_error Navigate to error page

But of course, as a retail product, UFile 2013's tutorial of course shows
correctly in Windows.

Apparently, Microsoft knows how often developers get confused by '/' and '',
and silently accepts such erroneous backslashes so that the relevant HTML Help
can be displayed.

The current Wine implementation of HTML Help, however, does not account for
such developer errors, leading to such blank HTML Help windows in (slightly)
buggy programs like UFile 2013.