A strange problem with IE and the browser helper object

Discussion in 'C++' started by Andrew Mayo, Dec 18, 2003.

  1. Andrew Mayo

    Andrew Mayo Guest

    (note: reason for posting here; browser helper object is written in
    C++; C++ developers tend to know the intricacies of message handling;
    this looks like a Windows messaging issue)

    Microsoft very kindly make available a DLL (the browser helper DLL)
    which allows you to trap and disable the context menu (right mouse
    click) and various 'built-in' browser accelerators (such as ctrl+P
    which brings up the print dialogue, and F5, which will refresh the
    current page) when using the browser.

    This is great, and I am duly grateful. However, using the helper DLL
    does have a strange side-effect which is annoying our users, and if
    anyone has an explanation, I'd be grateful.

    What happens is this. If you have any contenteditable fields in your
    page (and we have a *lot* of them

    e.g

    <span contenteditable>some editable stuff</span>

    and you host this page inside Visual Basic using the standard browser
    control

    then without the browser helper DLL attached to the page you can press
    the left mouse button and 'sweep' over the text to highlight it. This
    is of course a standard piece of Windows behaviour.

    Now attach the helper DLL. Now, you can no longer sweep across and
    highlight text. Instead, nothing happens.

    However, the keyboard still allows this e.g you can press HOME and
    CTRL+END to highlight text.

    I have tried running up Spy++ to see if somehow there's something
    weird going on with message handling but can't pin it down. The DLL
    source code doesn't seem to be screwing around with messages it didn't
    ought to be handling.

    Can anyone suggest a way of pinning down this rather strange problem?.

    I strongly suspect it is tied in with message handling/ accelerators
    or something weird in this area. I can't see obvious message eating
    but how Windows internally handles this I am not sure. I would assume
    that the destination hWnd sees a WM_LBUTTONDOWN and then captures the
    mouse and monitor WM_MOUSEMOVE messages to handle highlighting, but as
    this behaviour is intrinsic to the edit control, I don't see it
    documented anywhere. (of course, I assume that contenteditable text is
    implemented via an edit control - I have no idea how MS are doing it
    inside the browser).
    Andrew Mayo, Dec 18, 2003
    #1
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  2. On 18 Dec 2003 04:23:44 -0800, (Andrew Mayo) wrote:

    >(note: reason for posting here; browser helper object is written in
    >C++; C++ developers tend to know the intricacies of message handling;
    >this looks like a Windows messaging issue)


    Then post to a Windows group.

    [snip]

    Sincerely,

    Gene Wirchenko
    Gene Wirchenko, Dec 18, 2003
    #2
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  3. On 18 Dec 2003 04:23:44 -0800, (Andrew Mayo) wrote:

    >(note: reason for posting here; browser helper object is written in
    >C++; C++ developers tend to know the intricacies of message handling;
    >this looks like a Windows messaging issue)


    The question is off-topic in [comp.lang.c++].

    Try [comp.os.ms-windows.programmer.win32] instead. It's chock full of
    people programming Windows in C++. And other languages.
    Alf P. Steinbach, Dec 18, 2003
    #3
  4. Andrew Mayo

    Andrew Mayo Guest

    sorry. That would have been a better idea; was looking for an
    MS-specific C++ group and failed to find it, hence post.
    Andrew Mayo, Dec 19, 2003
    #4
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