window resize when textbox resize - wpf

Question

Here is the code for Textbox available in my window(form1.xaml),My requirement is when i am resizing my window i want to resize the textbox width also, How can i able to achieve this....
<TextBox Width="500" HorizontalAlignment="Left" Margin="5,0,0,5" TextWrapping="Wrap" AcceptsReturn="True" Text="{Binding Result,UpdateSourceTrigger=PropertyChanged,ValidatesOnDataErrors=True}" IsEnabled="{Binding OpenMode,Converter={StaticResource EnableModeConverter}}" Height="70" />

Answer 1

In WPF you typically place TextBox control within layout Grid control and set the ColumnDefinition Width property of that Grid cell to some relative value "*", so it will resize with the Window. Do NOT use a fixed Width="500" as per your sample: also, remove that "HorizontalAlignment="Left" (the default value is HorizontalAlignment="Stretch", so you can just omit it to simplify your XAML). See the following sample code snippet:
<Grid Name="Grid1">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="2*" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="*"/>
<RowDefinition Height="4*"/>
</Grid.RowDefinitions>
<TextBox Name="TextBox1" Grid.Row="0" Grid.Column="0" Height="70" Margin="5,0,0,5" TextWrapping="Wrap" AcceptsReturn="True" (...Rest of Your code) />
</Grid>
Note: The same technique could be applied to a vertical "Height" property in case you need to make it also resizable.
Hope this will help. Best regards,

Answer 2

Set HorizontalAlignment to Stretch, and don't set the Width
<Grid>
<TextBox HorizontalAlignment="Stretch"
Margin="5,0,0,5"
TextWrapping="Wrap"
AcceptsReturn="True"
Height="70" />
</Grid>

Answer 3

Layout in WPF is heavily depend on the parent container. For example, create a form with labels and input fields, consider using a Grid panel. Controls in WPF by default resize according to the layout behavior of their parent. Here is an example of a window with two labeled text boxes and two buttons that resize along with the window.
<Window>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<Label Content="Contact Name" Grid.Row="0" Grid.Column="0" />
<TextBox Grid.Row="0" Grid.Column="1" />
<Label Content="Contact Location" Grid.Row="1" Grid.Column="0" />
<TextBox Grid.Row="1" Grid.Column="1" />
<StackPanel Orientation="Horizontal" HorizontalAlignment="Right"
VerticalAlignment="Bottom" Grid.Row="2" Grid.Column="1">
<Button Content="OK" Width="75" Height="24" Margin="3" />
<Button Content="Cancel" Width="75" Height="24" Margin="3" />
</StackPanel>
</Grid>
</Window>