Datagrid problem

Question

Hi,
I am using a datagri control on my web page. I edit, update and cancel on this control.
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<asp:DataGrid ID="DataGrid1" RUNAT="server"  AutoGenerateColumns="False" 
  OnUpdateCommand="cmd_update" OnEditCommand="cmd_edit"
  OnCancelCommand="cmd_cancel">
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The problem is when I click the edit button, textbox's showing at rows which I want to edit. No problem at this point. But This textbox's width is too long and I want to edit this textbox's lengths. How may I do that?