Create DoubleAnimation and Animate a Button with Button.BeginAnimation and Button.WidthProperty
<Window x:Class="Window1" Title="Animation" Width="300" Height="300"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<Canvas>
<Button x:Name="b">OK</Button>
</Canvas>
</Window>
//File:Window.xaml.vb
Imports System.Windows
Imports System.Windows.Controls
Imports System.Windows.Media.Animation
Public Partial Class Window1
Inherits Window
Public Sub New()
InitializeComponent()
Dim a As New DoubleAnimation()
a.From = 50
a.[To] = 100
b.BeginAnimation(Button.WidthProperty, a)
End Sub
End Class