vovan,

Since you are using bound controls, any changes in the textboxes will be
reflected in the underlying datatable.

So you could use datatable.HasChanges to see if any changes have been made.

Kerry Moorman

Use the Enter and Leave events of the TextBoxes and CheckBoxes to Add and
Remove the Change handlers for those controls.

Here is an example for a checkbox--

   Private Sub CheckBox1_CheckedEnter(ByVal sender As System.Object, _
      ByVal e As System.EventArgs) Handles CheckBox1.Enter
       AddHandler CheckBox1.CheckStateChanged, _
           AddressOf CheckBox1_CheckedChanged
   End Sub

   Private Sub CheckBox1_Leave(ByVal sender As System.Object, _
        ByVal e As System.EventArgs) Handles CheckBox1.Leave
       RemoveHandler CheckBox1.CheckStateChanged, _
           AddressOf CheckBox1_CheckedChanged
   End Sub

   Private Sub CheckBox1_CheckedChanged( _
       ByVal sender As System.Object, _
               ByVal e As System.EventArgs)
       'add code here
   End Sub

When the user changes the check of a checkbox, the enter event will fire
first and add the checkchange event hander.  Then the checkstatechanged event
will fire and read the new value for the checkbox.

If you have a lot of textbox and checkbox controls, you could, (from within
the form_load event), consolidate your code by pointing all of the Enter
addhandler statements for one control type to a single code block, and
likewise for Leave.  If you do that, of course, the "sender" object is the
control that fired Enter or Leave, and you should use cast the objectly
appropriately...
directcast(sender, Textbox)

When you want to detect whether a change has been made for any control, you
have to come up with a monitoring system that captures original values after
the controls are populated.  If the user makes changes, comare the current
value to the original value, and set the flag for the control accordingly.  
If the user re-sets to the original value, your change flag should be reset
to false for that entry.  This also gives you an opportunity to have a Cancel
Changes button that restores all changes to the current record to their
current unchanged values.  You may be able to use the grid row as your
original values reference, but sometimes, by design, a grid will not show all
values that are shown in the controls on the form.