In most cases, these functions and objects duplicate functionality that you can find in other namespaces in the . They are necessary only when the Visual Basic 6.0 code model differs significantly from the . VB6 namespace are provided for use by the tools for upgrading from Visual Basic 6.0 to Visual Basic.By default you will see a red border around the UI element when this happens, e.g.if you are typing a letter into a Text Box bound to a source property of type int: The actual message that is describing the error is stored in the Error Content property of a objects in it, another attached property named Validation. To be able to see the error messages in the view you can replace the default control template that draws the red border around the element with your own custom template by setting the Validation.Public Class Form1 Private Sub Form1_Load(sender As Object, e As Event Args) Handles My Base. A common requirement for any user interface application that accepts user input is to validate the entered information to ensure that it has the expected format and type for the back-end to be able to accept and persist it.
A converter class converts data from one type to another during binding by implementing the Convert and Convert Back methods of the mentioned interface.Once you have created a converter class you will typically add it as a resource in XAML with a unique x: Key attribute and then reference it from the binding as a Static Resource: (string) to a dependency property of type string you don’t necessarily need to use a converter as the default conversion will automatically apply the To String() method on the value of the source property.This means that you don’t have to use a converter to display a If a user enters an invalid value that cannot be converted to an int and be set as the value for the Age property in the view model in the above example, a validation error will occur and a visual feedback will be provided to the user to indicate this.If you don’t specify a source explicitly by setting the Source property of the binding, it will inherit the Data Context from its parent element to use as its source.In a MVVM WPF application, the view model acts as the window’s Data Context: This means that that all controls inside the window will inherit its Data Context unless some parent element of a control overrides this by setting its own Data Context property.You can also change the appearance of the radio button control by using the Appearance property. Blue End Sub Private Sub Radio Button4_Checked Changed(sender As Object, _ e As Event Args) Handles Radio Button4. The following are some of the commonly used properties of the Radio Button control: Consult Microsoft documentation for detailed list of properties, methods and events of the Radio Button control. Green End Sub Private Sub Radio Button3_Checked Changed(sender As Object, _ e As Event Args) Handles Radio Button3. Elements in the adorner layer are rendered on top of the rest of the visual elements and they will not be considered when the layout system is measuring and arranging the controls on the adorned element layer.The adorned element in this case is the Text Box control itself and you include an in the control template where you want to leave space for it.The Radio Button control is used to provide a set of mutually exclusive options. If you need to place more than one group of radio buttons in the same form, you should place them in different container controls like a Group Box control.Let's create three radio buttons by dragging Radio Button controls from the Toolbox and dropping on the form.