Question

I am using Extended WPF toolkit’s DecimalUpDown control with its Value property binded to a Decimal? as follows:

   <extToolkit:DecimalUpDown Value="{Binding BlahBlah, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" ShowButtonSpinner="False" />

private Decimal? blahblah = 5;
    public Decimal? BlahBlah
    {
        get { return blahblah; }
        set { blahblah = value; }
    }

I noticed that as I key in the number in the textbox, the Value does not get updated until I click outside the control. Its ValueChanged event is not fired as well until I click outside.

I intend for the value to be updated as soon as the user changes the Value (i.e. real-time). Is there anyway to accomplish this?

Answer 1

I suspect that your binding parameter “gets lost” in the value transitions. The NumericUpDown controls internally bind a WatermarkTextBox to the Text property via TemplateBinding, to have the control respect your UpdateSourceTrigger it would probably need to be applied at that level. So due to this intermediate binding and the non-immediate synching between Value and Text you cannot control the source-update-behavior.