link button property to open in new tab?

try by Adding following onClientClick event.

OnClientClick="aspnetForm.target ='_blank';"

so on click it will call Javascript function an will open respective link in News tab.

<asp:LinkButton id="lbnkVidTtile1" OnClientClick="aspnetForm.target ='_blank';" runat="Server" CssClass="bodytext" Text='<%# Eval("newvideotitle") %>'  />

From the docs:

Use the LinkButton control to create a hyperlink-style button on the Web page. The LinkButton control has the same appearance as a HyperLink control, but has the same functionality as a Button control. If you want to link to another Web page when the control is clicked, consider using the HyperLink control.

As this isn't actually performing a link in the standard sense, there's no Target property on the control (the HyperLink control does have a Target) - it's attempting to perform a PostBack to the server from a text link.

Depending on what you are trying to do you could either:

1. Use a HyperLink control, and set the Target property
2. Provide a method to the OnClientClick property that opens a new window to the correct place.
3. In your code that handles the PostBack add some JavaScript to fire on PageLoad that will open a new window correct place.

Here is your Tag.

<asp:LinkButton ID="LinkButton1" runat="server">Open Test Page</asp:LinkButton>

Here is your code on the code behind.

LinkButton1.Attributes.Add("href","../Test.aspx")
LinkButton1.Attributes.Add("target","_blank")

Hope this will be helpful for someone.

Edit To do the same with a link button inside a template field, use the following code.

Use GridView_RowDataBound event to find Link button.

Dim LB as LinkButton = e.Row.FindControl("LinkButton1")         
LB.Attributes.Add("href","../Test.aspx")  
LB.Attributes.Add("target","_blank")