There are 726 articles on Google when you search "gridview thead". Most of them, and certainly all the first ones, talk about not being able to render thead, tbody and tfoot elements for NET 2.0 table based controls. But it's not so!

Each table row has a property called TableSection. If you set it to TableRowSection.TableHeader, TableBody or TableFooter, the specific tags will be created. Let me show a quick example of creating a THEAD element in a gridview:

gridView.HeaderRow.TableSection=TableRowSection.TableHeader;

And that's it. This kind of behaviour works for the Table WebControl and everything that derives from it or uses it to render itself.
However, the rendering of these elements inside the Table control is done simply with writer.RenderBeginTag(HtmlTextWriterTag.Thead), which gives no one the ability to change from .NET code the attributes of those sections. You can't have it all! You can use CSS, though. ex:

.tableClass thead {
  position:relative;
}

Usually, when I decide to blog on something, I do the testing and researching and installing first, then blog about it. But now I intend to use this cool site:
http://tredosoft.com/Multiple_IE
which boasts with installing all IE versions since 3.0 (oh, beloved 3.0) on the same computer without any problems. Since I am not a trusty guy, I blog about it before, then, if no one ever hears from me again, it means that no browser on any computer worked anymore after this :)

Well, without further ado, let me proceed :-SS
Extra info: http://www.positioniseverything.net/articles/multiIE.html

Step 1: Installing IE7.
Of course I had to validate my copy of Windows to download it, then I had to download all updates (even if I went to Windows Update right before installing IE7), then wait until it searched my computer for malicious software, then installing everything. You can't imagine a smoother installer. It just tells you to wait and does everything in the background, showing you meaningless text labels, a cool progress bar and, of course, asking you to close everything before and restart Windows after the installation.
But it worked, and I am not writing this from Firefox :)

Step 2: Installing multiple-ie-setup.exe
Wow! It took around 1 minute to install everything. Of course, not everything is going as smoothly as planned. First of all, I can't see Blogger (and suposedly not any other cookie using site) in IE6.0. Then, it redirects me to a nocookies.html files that doesn't exist :-/ But that's a Blogger issue. The Options menu in IE6.0 is actually the IE7.0 menu and the settings for cookies cannot be overriden. Actually, you can, but the settings won't save.
After looking at the TrendoSoft site, I've noticed that this bug is considered solved, even if some of the people seem to continue to have problems. So I've tested more throughly. Session variables seems to be saved, but Blogger continues to take me to the nocookies page. Also, AjaxPro, the ajax library I am using, doesn't seem to work with IE 6.0.

All in all it seems a pretty functional program. However, the type of sites that I am building have certain characteristics that seem not to work with it. I will try to log on TrendoSoft and get the problem fixed, but I guess Yousif did the best he could so far and resolving every issue I have will be hard if not impossible.

Amirthalingam Prasanna's article about the transactional model in NET 2.0.

As far as I understand, the old declarative ADO.NET Begin/RollBack/CommitTransaction model has become obsolete and a new TransactionScope model is used in NET 2.0. You have to add the System.Transactions.dll file to your references.

Basically, the C# code is like this:

using (TransactionScope scope=new TransactionScope
                       (scopeOption,transactionOptions,interopOption)) {
    // do database ops

    // if everything is alright
    scope.Complete();
}

scopeOption is an enum of type TransactionScopeOption, with the options Required (requires a transaction and uses if there is already on open), RequiresNew (always opens a new transaction), Suppress (don't use a transaction, even if one is open)

transactionOptions is of type TransactionOptions which has two interesting properties: IsolationLevel and Timeout.

interopOption is an enum of type EnterpriseServicesInteropOption and specifies how distributed transactions interact with COM+ transactions.

But what about the old NET1.1 framework? Doesn't it have something like that? Here comes Alexander Shirshov with help:
TransactionScope in .NET 1.1

Well, basically, you can't do it.
I am looking at the internal ParseSortString(string sortString) in the DataTable object of NET 1.1, where the first thing the method does is to split the string by commas, then check for square brackets. This insures that there is no way to sort datatables by columns with commas in their names. The funny thing is that the filtering expression is treated like royalty by an ExpressionParser object, and allows column names with commas inside.
Now let's check the code for NET 2.0. It's identical.

The solution is a little annoying code like this:

private DataRow[] SelectSafe(DataTable dt, string filter, string sort)
{
  var columns = new string[dt.Columns.Count];
  for (var c=0; c<dt.Columns.Count; c++)
  {
    columns[c] = dt.Columns[c].ColumnName;
    if (dt.Columns[c].ColumnName.IndexOf(',')>-1)
    {
      dt.Columns[c].ColumnName = dt.Columns[c].ColumnName.Replace(',', ';');
      // assume that the column name was bracketed correctly in the select
      sort = sort.Replace(
        "[" + columns[c] + "]",
        "[" + dt.Columns[c].ColumnName + "]");
    }
  }
  var dr = dt.Select(filter, sort);
  for (int c=0; c<dt.Columns.Count; c++) {
    dt.Columns[c].ColumnName = columns[c];
  }
  return dr;
}

I am sure there is more elegant code, but this seems to be the only solution so far except manually sorting a DataTable.

The whole meeting took place at the Titulescu room at RomExpo. They had 4 desks that spanned the alphabetical ordering of software firms participating, so the entry was really comfortable. They gave us a pen and a little notebook to take notes, too. The whole meeting lasted from 9:00-16:30, then there was an hour of free talks.
My general impression of the briefing was good. The presenters were enthusiastic and talked about: application development on Windows Vista with NET 3.0 and Sharepoint and Office 2007. The new Microsoft XML office format was presented, programatic methods of accessing and creating them, how to mix Sharepoint and Office in order to create quick Excel based web sites, etc. The most interesting part, though, was of course the last. It presented the advances in programming technology like the C# 3.0 features and ADO.Net vNext. Too bad I've already read about those technologies, but the enthusiastic presentation mode (alas, SPOKEN TOO LOUD) was refreshing.
The information was as compacted as possible, but there was too little code for me, even if most presenters seemed to have the same hatred for marketing slides as I did.
There were also 30 minutes of coffee break and 1 hour of lunch. The lunch food was very good and varied, from chinese apetizers like sesame meatballs and Shanghai chicken to sandwiches, salads and sweets. Taking into account that I've been to a similar Microsoft thing in Milano, where they barely gave us some sandwiches in plastic bags, this was truly great.

Whoa! Big title there. This article applies to errors in ASP.NET 2.0 when trying to dynamically render a gridview with paging.

I have been trying to "Ajaxify" my web programming and I've found that the easiest method is to wrap everything I need in Web User Controls, render the controls, then send the rendered string through ajax to fill some innerHTML.
Well, the fine people at Microsoft thought otherwise. I have been trying to render a web user control with a gridview inside it for 3 hours now and nothing helped. I kept getting a NullReferenceException when calling GridView.DataBind and the StackTrace showed it originated in the BuildCallBackArgument(int) method.
Nothing helped except actually decompiling the code of the GridView itself. I've found out that it called a method in the Page of the control, in other words it needed a page. I gave it a page, but then another problem occured that I'd already solved here. I already had a parent page that overrode the offending method, so the final code is this:

ParentPage pp=new ParentPage();  // where ParentPage is a Page with VerifyRenderingInServerForm(Control control) overriden so it doesn't do anything
pp.EnableEventValidation = false; //another silly error
uc.Page = pp; //uc is the user control needing rendering
uc.Bind();

Unlike .NET C# (or most other programming languages), the Javascript replace function only replaces the first instance of a string. To replace all the instances, you need to use regular expressions.
Simon Willison's Weblog contains a good article on this.

Basically, if you use str1.replace(str2,str3) it will return str1 with the first occurence of str2 replaced with str3. If you use str1.replace(regexp1,str3) and the regular expression has the g modifier it will return str1 with all matches of regexp1 replaced with str3.

A regular expression looks like : /searchpattern/modifiers.
You can create a regular expression from a string by using the

new RegExp(str2,modifiers)

syntax.

The problem comes when you want to create a regular expression from a variable that may contain regular expression escape sequences. Here is Simon Willison's function that "escapes" the string in order to use the RegExp syntax safely, slightly modified to contain the '^' character:

RegExp.escape = function(text) {
  if (!arguments.callee.sRE) {
    var specials = [
      '/', '.', '*', '+', '?', '<', '>',
      '(', ')', '[', ']', '{', '}', '\\', '^'
    ];
    arguments.callee.sRE = new RegExp(
      '(\\' + specials.join('\\') + ')', 'g'
    );
  }
  return text.replace(arguments.callee.sRE, '\\$1');
}

Example: str=str.replace(/\\/g,'\\\\') (replace slashes with double slashes)

I have found three basic methods:

1. Use an online type of viewer.
   You select the resolution, type in the URL of your site, then sit back and relax.
   I see a lot of problems for this method:
   
   • you don't want everybody to know you are working on a site
   
   
   • you don't want the site to be open to the public while you work on it
   
   
   • you need an internet connection
   
   


2. Use an external program.
   BrowserSizer is as good as any. It's free and easy to use. You select the resolution and it resizes your IE window accordingly.
   The only problem I see is that you need the program. You install it, it messes with your browser settings, etc.


3. Use a javascript script in the IE addressbar:
   

   javascript:db=document.body;bst=db.style.zoom=1;rd=prompt("Width:",800);
   db.style.zoom=db.offsetWidth/rd;void('')

   
   Unfortunately, the zoom messes up quite a few things, including fixed table headers or custom javascript controls. However, I do believe it is the best solution for most situations.
   

You may experience unexpected results when you open a Web page that is in an ASP.NET 2.0-based application in Mozilla Firefox and the DefaultButton property is assigned to a LinkButton control or an ImageButton control

Just a reminder of a bug I am likely to encounter. The obvious solution is to use ControlAdapters or inheritance to create LinkButtons and ImageButtons that are rendered as buttons.

I've accidentally stumbled upon FxCop, a Microsoft free tool that analyses the generated NET code (.exe or .dll) for bad design practices.
While many of the errors and warnings I got were related to casing, a lot of them were not and they had come with links, extended information and solutions. The rules that FxCop has help you to make members static if none of the instantiated object's properties or members are used in it, use case insensitive String.Compare instead of comparing two ToLower strings, or StringBuilder in loops, use NET 2.0 constructs instead of 1.1 ones, etc.
I find it at least interesting and I intend to use it in my future software projects.

ASP.NET 2.0 has this nice feature called Virtual Path Providers. What it
actually does is enable you to get your site files from anywhere using an
override of the VirtualPathProvider class.

Virtualizing Access to Content: Serving Your Web Site from a ZIP File
This is a very nice article where a Microsoft guy shows how to run a
complete ASP.NET site from a ZIP arhive. Just two lines of code in
global.asax , a standard web config file and a ZIP arhive.

This opens up a lot of possibilities, like reading the ASPX or CS files from
a class that creates them dynamically, or reading the files from multiple
sources at once. Yummy!

I vaguely remember reading of nullable types in the C# 2.0 "what's new" documentation, but somehow it slipped by me. Now I've stumbled over this useful new feature and I can explain it for a bit.
Here is the Microsoft explanation.

Basically you can declare any value type as nullable by using the syntax <type>?.
Example: int? x=null;
There is even a nice operator ?? that acts like the SQL isnull function.
Example: int y=x ?? 0;
The two above examples are the short for the following:
System.Nullable x=null;
int y=x==null?0:x.Value; int y=x.HasValue?x.Value:0; OR int y=x.GetValueOrDefault(0)

The Nullable type has some nice methods:

• GetValueOrDefault([value]) - gets the default value or the specified value when the nullable type is null


• HasValue() - something like is not null

There is no IsNull method to the Nullable type. Also, x=null makes x==null true, as opposed to, let's say, the SqlInt32 type.

I was stunned today to see that a site that I was working on was not starting because of this idiotic error:
ASP.NET 2.0 Parser Error Message: Access to the path '[something.cs]' is denied.
And further down:
No relevant source lines

The only thing I remembered doing was close the project in Visual Studio and work on another. I tried starting the site with the URL, without loading it into Visual Studio and the error occured. If you search on the net this error, you will see that there are a lot of articles that talk about the ind*exing ser*vice, but I stopped it a long time ago. So what was going on?

• The file was accessible


• The file was not opened by another application


• I could freely delete/remove/modify the file

In desperation I compared the Security settings for this file with other files in the directory. To my surprise, there was a major difference. The files that were accessible had a lot of users with access rights to them, the file that gave the error had around three.

I have no idea what caused this. I just copied the same rights from the other files to the problematic one and it worked. I am using Visual Studio 2005, Resharper and SourceSafe. Do you also hear the Twilight Zone soundtrack?

It's is done in two different ways: the IE way and the DOM way.
IE way) really simple, use element.fireEvent(eventName,[eventObject]), where element is a HTML element and eventName is something like "onclick";
DOM way) really complicated. A short example:

function simulateClick() {
  var evt = document.createEvent("MouseEvents");
  evt.initMouseEvent("click", true, true, window,
    0, 0, 0, 0, 0, false, false, false, false, 0, null);
  var cb = document.getElementById("checkbox");
  var canceled = !cb.dispatchEvent(evt);
  if(canceled) {
    // A handler called preventDefault
    alert("canceled");
  } else {
    // None of the handlers called preventDefault
    alert("not canceled");
  }
}

As you can see, you need to create the event, then initialize it, then dispatch it.

Things you need to take care with:

• in the DOM model the event name is not prefixed with "on". In the IE way, the event is prefixed with "on". ex: DOM:click IE:onclick.


• in the DOM model the event triggering does everything the event would have done, like setting a value, in IE it does not. ex: triggering onclick in the above example would check or uncheck the box. In IE you need to change the value yourself.

This is code I did to programatically click a checkbox and also trigger the onclick event:

if (box.onclick)        
    {
        if (box.dispatchEvent) {
            var clickevent=document.createEvent("MouseEvents")
            clickevent.initEvent("click", true, true)
            box.dispatchEvent(clickevent)
        } else
        if (box.fireEvent) {
            box.checked=!box.checked;
            box.fireEvent('onclick');
        } else
            box.onclick();
    } else box.checked=!box.checked;

Microsoft has now released Orcas into the wild with a Community Technology Preview download. Links: Orcas CTP download, Orcas CTP - Development Tools for WinFX.

A quick intro interview with Sam Guckenheimer, Lead Product Planner for Orcas:
Orcas and the Future of Visual Studio