How can I stop WebBrowser control from ignoring setting DocumentText values?

Hi Guys,

I have a WinForms user control that contains a WebBrowser which is used to edit HTML, and it used to work perfectly.  Lately a number of users have reported that it does not display the HTML assigned to it, and this proves consistently to be the case.  I am not yet certain whether the issue relates to the OS (32 vs 64 bit, XP or Windows 7) or whether it relates to a security update, but I do know that it used to work a treat and now the WebBrowser stays blank.  As far as I am aware nothing has changed in the control code, and this seems to be confirmed by source control.

I have seen many mentions of this issue and suggestions for resolutions on the web and have tried every one I have found, but still nothing!

Here is the basic code that initialises the WebBrowser:
            // Web Browser
            webBrowserBody.DocumentText = string.Empty;
            
            if (webBrowserBody.Document != null)
            {
                webBrowserBody.Document.Click += WebBrowserBodyDocumentClick;
                webBrowserBody.Document.Focusing += WebBrowserBodyDocumentFocusing;
                webBrowserBody.Document.ExecCommand("EditMode", false, null);
                webBrowserBody.Document.ExecCommand("LiveResize", false, null);
            }
            
            webBrowserBody.AllowNavigation = false;
            webBrowserBody.AllowWebBrowserDrop = false;
            webBrowserBody.IsWebBrowserContextMenuEnabled = false;
            webBrowserBody.ScriptErrorsSuppressed = true;

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Here is how the bodytext is set:
        public override string Text
        {
            get { return webBrowserBody.DocumentText; }
            set { webBrowserBody.DocumentText = value; }
        }

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Here is an example of the HTML retrieved from a database that is being assigned using the getter:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META content="text/html; charset=utf-8" http-equiv=Content-Type>
<META name=GENERATOR content="MSHTML 8.00.6001.18928"></HEAD>
<BODY><FONT size=2 face=Arial>
<P>You received a new telephone message at %%MessageTime%% on 
%%MessageDate%%</P>
<HR>
<BR>
<P><STRONG>Caller: </STRONG>%%Caller%%<BR><STRONG>Company:</STRONG> 
%%CallerCompany%%<STRONG><BR>Telephone: 
</STRONG>%%CallerTelephone%%<BR><STRONG>Email:</STRONG> %%CallerEmail%%</P>
<P><STRONG>Message:</STRONG><BR>%%TelephoneMessage%%</P>
<P>
<HR>

<P></P>
<P>%%User%%<BR>%%CompanyName%%<BR>%%CompanyMailingAddress%%<BR>%%CompanyWebInfo%%</FONT><BR></P></BODY></HTML>

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We know that the HTML is valid and works, because we can assign it to an Outlook email and it works perfectly...

Any suggestions as to how I might get this working again?
LVL 3
chrisbrayAsked:
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Bob LearnedCommented:
I have Windows 7 Enterprise 32-bit, and the WebBrowser control won't display HTML, unless I comment out this line:


webBrowserBody.Document.ExecCommand("EditMode", false, null);

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chrisbrayAuthor Commented:
Hi Bob,

Hmm...  that made no difference on my 64 bit machine, and so far appears to work on 32 bit XP.
Bob LearnedCommented:
Also, I have IE 9 installed...9.0.8112.16421
chrisbrayAuthor Commented:
Hi Bob,

OK, found a workaround:

        private void SetHtml(string value)
        {
            if (webBrowserBody.Document != null)
            {
                webBrowserBody.Document.OpenNew(true);
            }
            else
            {
                webBrowserBody.Navigate("about:blank");
            }

            if (webBrowserBody.Document != null)
            {
                webBrowserBody.Document.Write(value);
            }
        }

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This relies on the following line in the webBrowser initialisation:

webBrowserBody.AllowNavigation = false;

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If you wanted you could include it in the setting method.

This code was proposed by Andrew Ransom back in 2007 at http://www.codekeep.net/snippets/1bb8c968-3f30-46ee-96e6-006161a0c04b.aspx indicating that something else has changed in our code if the problem was extant in .Net even then - I know that our dialogs have all worked after that because they were barely thought of at that time....

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chrisbrayAuthor Commented:
The answer was found based on a snippet posted by a third party.

Thanks as always to TheLearnedOne who always makes every effort to help.
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