WinForms binding

Question

I have some controls bound to a BindingSource control.

I want to do a calculation when the value changes in one control and set the result on another control.

Do i update the textbox the property is bound to or do i update the underlying entity which would update the control anyway(i hope)?

When i change comboboxA(onpropertychange)...textbox B is updated with the new calculated result..this works fine...but i have noticed that when i Leave combobox A..combobox A reverts back to its original value...what is going on here!

Private Sub ComboBoxEditCostCode_EditValueChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBoxEditCostCode.EditValueChanged
        Select Case ComboBoxEditCostCode.EditValue
            Case "7" 
                CType(TransactionEntityBindingSource.Current, TblTransactionsEntity).Qbdescription = "7-is here" 

            Case "2" 
                CType(TransactionEntityBindingSource.Current, TblTransactionsEntity).Qbdescription = "2-is here" 

            Case Else
                CType(TransactionEntityBindingSource.Current, TblTransactionsEntity).Qbdescription = "7-is here"
        End Select
End Sub

Answer 1

Tell more about your changing, how second text box is bound?
You have to change your initial data instead of changing textbox b value.
Also when textbox A loses it focus raises EndEdit event and I think binding mechanism refreshes value in textbox B.
You can control on which action editing is done when you setting your binding to textboxes.

Answer 2

if we bind a control to a source, then if the source changes, we can make the its value automatically reflected in the control. About the problem you are facing, it would be better if you show the code snippet.