How to create Expandable TextBox in Wpf
Step 1: Right click on project Step 2: Click on Add and select New Item Step 3: Search for Custom Control Step 4: Select Custom Control(WPF) Step 5: Write ExpandableTextBox in Name and click on Add It will create one class with the Name ExpandableTextBox with following code: namespace CustomControl.Controls { public class ExpandableTextBox : Control { static ExpandableTextBox() { DefaultStyleKeyProperty.OverrideMetadata(typeof(ExpandableTextBox), new FrameworkPropertyMetadata(typeof(ExpandableTextBox))); } } } It will also create a folder called Themes inside this folder it will create ResourceDictionary with the Name Generic with folowing code: Generic.xaml <ResourceDictionary xmlns:local="clr-namespace:Wpf" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"> <Style TargetType="{x:Type local:ExpandableTextBox