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Click on LinkButton in Gridview: why is the Grid reloaded most of the times but not always?

I´m trying to understand the annoying refreshment of the GridView/Repeater that occurs most of the times I click on a LinkButton within that element. If this is caused by the Postback, then why doesn't it happen all the times?
And if it is not caused always, do I might even get rid of it?
I usually do this to get detailed information on a cell clicked in a Grid or repeater:
<asp:LinkButton ID="ButtonSelect" runat="server" CommandName ="Select" CommandArgument = '<%# Eval("date") %>' Text='<%# Bind("TAG") %>' OnClick="GetDetails"/>
The data processed in the "GetDetails" method will then be displayed in some other element. There wouldn't be any need to refresh the Grid.
Is this the normal behavior for any LinkButton click in a GridView?
Martin

It's the normal action of a server button within a gridview. It will cause a postback. A postback will force the Page LifeCycle. The entire page will be recreated and Databinding may or may not occur depending on your cache options and programming.
"Fixing" that really depends what you are trying to accomplish. If it's simply to stop the "screen flicker" due to the postback, consider using AJAX calls or <asp:UpdatePanel> server controls.
If you are trying to work with JS on the clientside and just wish to defer the postback until later, convert the button to a template field and replace the <asp:LinkButton> with a basic html control <a href="javascript:void();" ...>, <button type='button'>, <input type='button' ..., etc...

Why label's value is changed?

I know even if the ViewState is disabled for the TextBox, we are not losing the data because it implements the IPostBackDataHandler interface.
<asp:TextBox ID="TextBox1" runat="server" EnableViewState="False"/>
But my question is why this happens for label too? Why label is not losing it's data even if the ViewState is disabled since the label doesn't implements the IPostBackDataHandler interface?
<asp:Label ID="Label1" runat="server" EnableViewState="False" ViewStateMode="Disabled"/>
TextBox definition:
public class TextBox : WebControl, IPostBackDataHandler,
Label definition:
public class Label : WebControl, ITextControl
My code:
<form id="form1" runat="server">
<div>
<asp:Label ID="Label1" runat="server" EnableViewState="False" ViewStateMode="Disabled" Text="Before click"></asp:Label>
<asp:TextBox ID="TextBox1" runat="server" EnableViewState="False"></asp:TextBox>
<asp:Button ID="Button1" runat="server" Text="Button" OnClick="Button1_OnClick"/>
</div>
</form>
And code behind:
protected void Button1_OnClick(object sender, EventArgs e)
{
Label1.Text = "Changed.";
}
I expected to see the "Before click" in my label after I clicked the button but I see the "Changed" text in my label after I clicked the button.

Ok I deleted my previous answer, I will try to re-state it with an example.
First, as others stated, the idea of ViewState is to hold the state between postbacks, rather than during a single page load cycle, so what you're seeing is the expected behavior.
To see the difference with an example, try adding your label with 2 buttons:
<asp:Label ID="Label1" runat="server" EnableViewState="False" Text="Before click"></asp:Label>
<asp:Button ID="btn1" Text="Click" OnClick="btn1_Click" runat="server" />
<asp:Button ID="btnReset" Text="Reset" OnClick="btnReset_Click" runat="server" />
Where btn1 sets the value to "Changed", and btnReset has an empty handler.
Now with EnableViewState set to False, if you click on btn1 the page reloads, btn1_Click is executed, and the page is rendered with the label value = "Changed", if you click btnReset the page will reload again, but since view state is disabled, the label will revert to its original text "Before click"
If you set EnableViewState to True on the lable and click btn1 then btnReset, the label value will stay as "Changed", since the state is kept during postbacks
Hope that clarifies things a bit

This is going to be long and detailed.
Let's start with this markup. Almost identical to yours, with one additional button and a label. I'll explain why we need them later.
<form id="form1" runat="server">
<div>
<asp:Label ID="Label1" runat="server" EnableViewState="False" ViewStateMode="Disabled" Text="Before click"></asp:Label>
<asp:TextBox ID="TextBox1" runat="server" EnableViewState="False"></asp:TextBox>
<asp:Button ID="Button1" runat="server" Text="Button" OnClick="Button1_OnClick"/>
<asp:Label ID="Label2" runat="server" Text="Blah" />
<asp:Button ID="Button2" runat="server" Text="Button" OnClick="Button2_OnClick"/>
</div>
</form>
And we'll use this code behind. Again, I'll explain the purpose of the second handler later on:
protected void Button1_OnClick(object sender, EventArgs e)
{
Label1.Text = "Changed";
}
protected void Button2_OnClick(object sender, EventArgs e)
{
Label2.Text = Label1.Text;
}
Let's see what happens when we initially load the page. First ASP.NET reads all the markup, and then goes through the page life cycle with all the events. In markup parsing stage Label1 gets assigned text Before click, and it is never changed later during initial load. So later during rendering phase this is what is getting rendered into HTML and sent to browser. Thus Before click is displayed on the screen. Nice and easy.
Now we click Button1. Postback occurs, which is a term that describes a request sent to the same page by one of its controls after it was initially loaded. Again, everything starts with ASP.NET parsing the markup, and again Label1 gets assigned text Before click. But then page life cycle events happen, including control event handlers. And in the handler for Button1 the text of Label1 is changed to Changed. Now here is the important thing to note: if ViewState for the Label1 was enabled, this new value would be stored in there, and so called tracking would be enabled for property Label1.Text. But ViewState is disabled, and so the new value is not stored anywhere except Label1. Next comes the rendering page stage, and since Label1.Text still holds the value Changed this is what is rendered into HTML and sent to the browser to display. Note however that this new value is not sent inside the ViewState field. As you can see, whether ViewState is enabled or not plays no role in what is displayed after this postback.
Now we'll click Button2, which would trigger another postback. Again, ASP.NET parses the markup, again Label1 gets text Before click. Then comes ViewState loading part. If ViewState for Label1.Text was enabled, it would load changed value into this property. But ViewState is disabled, and so the value stays the same. Thus, when we reach Button2 click handler, the value of Label1.Text is still Before click, which is assigned to Label2.Text. But Label2 has ViewState enabled, and so this new value for its text is stored in ViewState and sent to the client (ViewState is implemented as a hidden field on the client side). When everything gets to the browser, we can see Label1 and Label2 both displaying Before click.
And to nail it down we'll do a third postback, now clicking Button1 again. Just as during the first postback, Label1 ends up with Changed text. But what about Label2? Well, this one has ViewState enabled, so during initial markup parsing ASP.NET assigns it the value Blah, and during ViewState loading it replaces this value with Before click. Nothing else affects this value during the page life cycle (we did not click Button2 this time), and so we end up seeing Changed and Before click in the browser.
Hopefully it makes it clear what the ViewState is for and what disabling it does. If you want to dive even deeper into how ViewState works, I would greatly recommend this article: TRULY Understanding ViewState.

I think you have wrong understanding what ViewState is.
Data in ViewState is being stored BETWEEN requests, but not DURING page lifecycle.
BTW - ViewState data is generated after PreRenderComplete event in SaveStateComplete event.
https://msdn.microsoft.com/en-us/library/ms178472.aspx
If you have ViewState switched off - just think that it will not be generated in output.
During page lifecycle all data assigned to controls(and also to page fields and properties, as the page is just a class) will be rendered as you defined in aspx. But will be lost after, unless is saved in ViewState.

FreeTextBox javascript error is preventing PostBack on my DropDownList

I have one page with 3 FreeTextBox controls on it. They are set up correctly, and I was using them normally until I needed to add a DropDownList control that would PostBack to the server, but I was surprised to see that the OnSelectedIndexChanged event would never trigger. If I was to do a Post with a button, or some other server-side control, then would the event be triggered. After much debugging I found the following Javascript error was being thrown every time I selected something different on my DropDownList control:
TypeError: FTB_API.MainContent_MainContent_FreeTextBox1 is undefined
The error seems pretty straight forward;
Firebug tells me this error comes from the following function:
function WebForm_OnSubmit()
{
FTB_API['MainContent_MainContent_FreeTextBox1'].StoreHtml();FTB_API['MainContent_MainContent_FreeTextBox2'].StoreHtml();FTB_API['MainContent_MainContent_FreeTextBox3'].StoreHtml();
return true;
}
I've tried several things without success. When I remove the FreeTextBox controls from my page, I have successful PostBacks. Any help would be appreciated.
Thanks.
EDIT 1: This is some of my markup
3 FreeTextBox set up like this:
<FTB:FreeTextBox ID="FreeTextBox3" JavaScriptLocation="ExternalFile" ButtonImagesLocation="ExternalFile" ToolbarImagesLocation="ExternalFile" runat="server" EnableHtmlMode="true" />
My DropDownList:
<asp:DropDownList ID="DropDownList1" runat="server" AppendDataBoundItems="true" AutoPostBack="true" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged">
</asp:DropDownList>

Set the property AutoPostBack = true of your dropdown in markup page. This will make the post back when you change the dropdown element and OnSelectedIndexChanged get triggered.
Example :
<asp:DropDownList id="drpList" runat="server" AutoPostBack="true" OnSelectedIndexChanged="event name" />

I have found the answer to the question in this thread: Hidden FreeTextBox bug on Firefox It seems for some reason that when the control is not visible or is hidden (I have tabs) it behaves this way. The answer is kind of a Hack, but it works. Thanks for the answers.

Linkbutton OnCommand not firing after upgrading to .Net 4

I have a webforms project that was written in ASP.Net 3.5 and works fine. I decided to upgrade it to 4.0 for various reasons. The upgrade went fine. However, on one particular page, I have certain linkbuttons that fire an event in code behind. The event never fires on click. Other controls on the page, like an link button with client side code and Telerik radgrid work fine.
This Works
<asp:LinkButton ID="InsertLinkButton" runat="server">
<asp:Image ID="ImageButton1" runat="server" />Add New Employee</asp:LinkButton>
//Code behind adding javascript event
InsertLinkButton.Attributes["onclick"] = String.Format("return ShowInsertForm();");
This Doesn't
<asp:LinkButton ID="ALinkButton" runat="server" CommandName="A" OnCommand="LinkButton_Command" ">A</asp:LinkButton>
The page is a content page with a master page. Any ideas?

I'm not sure if this is just a typo on your post but your markup isn't correct on the LinkButton.
It is currently:
<asp:LinkButton ID="ALinkButton" runat="server"
CommandName="A" OnCommand="LinkButton_Command" ">A</asp:LinkButton>
It should be:
<asp:LinkButton ID="ALinkButton" runat="server"
CommandName="A" OnCommand="LinkButton_Command">A</asp:LinkButton>

The panel containing the controls was referenced as an updated control in a Telerik RadAjaxManager buried in the mark up. If I removed the RadAjaxManager, it worked. Apparently the linkbutton command event didn't fire the ajax callback. Since this worked in 3.5, I'm wondering if some metadata didn't get converted properly during the 3.5>4 upgrade?
Anyway, I updated the references of what was supposed to fire an ajax call from the RadAjaxManager and it now works. Thanks for the help!

UpdatePanel and Repeater render page unresponsive after post-back

I have a page with an UpdatePanel that contains a Repeater and a text box with the number of items in the repeater. When I change the value, the page is supposed to post back and redraw the Repeater with the updated number of items. This works in principle, but the page ends up frozen after post-backs and does not accept any input - in IE 8 only. It works perfectly fine in Firefox. For instance, the context menu does not appear when I right-click in controls, and I cannot enter text in text boxes.
When I take out the UpdatePanel, the page works fine, but of course refreshes on every post-back event. This is not necessarily related to the Repeater on the page. I think I am seeing this on other pages. What's the trick here?
<asp:UpdatePanel ID="uPanel" runat="server" UpdateMode="Conditional"
EnableViewState="true" ChildrenAsTriggers="true">
<ContentTemplate>
<asp:Panel ID="Panel1" runat="server" DefaultButton="btnSubmit">
<asp:TextBox ID="tbItems" runat="server" AutoPostback="true"
OnTextChanged="textchanged_Items"/>
<asp:Repeater id="rptItems" runat="server"
OnItemDataBound="repeaterItem_Databound">
<...>
</asp:Repeater>
protected void textchanged_Items(object sender, EventArgs e) {
try {
// this methods rebinds the repeater to a List after changing
// the number of items in the list
ReflowItemRepeater();
// This is not really necessary, since Databind() appears to
// cause an update. I tried it anyways.
uPanel.Update();
}
catch (Exception ex) {
ShowError(this, "Error displaying the item list.", ex, true);
}
}
I ended up removing the update panel.
One month later, different page, I am still and again fighting this. The situation is the same.
An update panel, a repeater (actually 2 nested repeaters), and a control in the repeater that fires a postback event. The server processes the event correctly and returns control, but the browser (IE8) never refreshes the update panel. The page is unresponsive, as if in some sort of dead-lock situation. I can unlock it by clicking on a button that fires another postback event (also in the update panel). But the text boxes in the panel are not clickable or editable when this happens.
Also, it happens only the first time. Once I have "freed up" the lock, or whatever it is, it will not happen again on this page, even when I repeat the exact same steps that led to it.
When this happens, the JIT debugger does not report anything.

I would actually set Triggers within your updatepanel.
I'm not sure you need to call .Update in your code behind as the updatepanel will be updated when the trigger occurs.
Try this:

My gut feeling is that it has something to do with the use of the OnTextChanged event. For kicks, try adding a button next to the text box, and reflow the repeater when the button is clicked instead. Does IE still freeze?

So I stripped this page down to the minimum and I found out what is doing it - the AjaxToolkit:CalendarExtender. If I take it out, everything works fine. Still, I would be curious to know if there is a workaround.
Here is a link to my test page. I will keep it up for a few days.
To see the issue, select "2" from the drop-down, then type something into the first quantity field and tab out. The cursor will blink in the next field, but it does not allow input. This happened in IE8, not in Firefox.
Edit: Actually, when I went back to the full page and removed the CalendarExtender, it was still not working. I do suspect that this issue has to do with controls posting back in the UpdatePanel, but I just can't pin it down. It seems seems to be one of these things where a combination of x things does not work, while any combination of (x-1) things does work.

Regarding the initial question, here's a working sample. I don't know if it's anyhow helpful, but just to make sure...
<%# Page Language="C#" %>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server"><title>Ajax Test</title></head>
<body>
<form id="form1" runat="server">
<asp:ScriptManager runat="server" />
<asp:UpdatePanel runat="server" ChildrenAsTriggers="true">
<ContentTemplate>
<asp:Label runat="server" AssociatedControlID="txtTest">
Enter 'fruit' or 'vegetables':
</asp:Label>
<asp:TextBox
runat="server" ID="txtTest" AutoPostBack="true"
OnTextChanged="Handler_Test_TextChanged"
/>
<asp:Repeater runat="server" ID="rptItems">
<HeaderTemplate><ul></HeaderTemplate>
<ItemTemplate><li><%# Container.DataItem.ToString() %></li></ItemTemplate>
<FooterTemplate></ul></FooterTemplate>
</asp:Repeater>
</ContentTemplate>
</asp:UpdatePanel>
</form>
</body>
</html>
<script runat="server">
static readonly string[] Fruit = new string[]
{ "Apples", "Oranges", "Bananas", "Pears" };
static readonly string[] Veg = new string[]
{ "Potatoes", "Carrots", "Tomatoes", "Onion" };
void Handler_Test_TextChanged(object s, EventArgs e)
{
if(txtTest.Text == "fruit") rptItems.DataSource = Fruit;
else if(txtTest.Text == "vegetables") rptItems.DataSource = Veg;
else return;
rptItems.DataBind();
}
</script>