WPF - can't see a button in th View design - wpf

Question

I wrote a simple WPF window that shows a customers grid.
in the bottom of the grid I added a button "Add a new Customer, but it blended into the background of the window, and I can't see it in View design.
this is the code:
<Window x:Class="NihulMlay._1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title=" Customers " Height="120" Width="600">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="300" />
<ColumnDefinition Width="300" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="40" />
<RowDefinition Height="40" />
</Grid.RowDefinitions>
<Button FontWeight="Bold">Customer name</Button>
<Button Grid.Column="1" FontWeight="Bold">Name</Button>
<Label Grid.Row="1"></Label>
<Label Grid.Column="1" Grid.Row="1"></Label>
<Button Grid.ColumnSpan="2" Content="Add a new Customer" HorizontalAlignment="Left" Height="100" Margin="270,114,0,-173" Grid.Row="1" VerticalAlignment="Top" Width="75"/>
</Grid>
</Window>
thanks.

Answer 1

Your Problem is the Window height of 120, once you resize it to say 350, you can see the Button.
The margin on your Button is:
Margin="270,114,0,-173"
which makes a Top-Margin of 114, the Button height is 100 and the row above is set to 40. This values alone would make a total required height of 254 to see all contents.

Answer 2

I think you are mistaking a Grid with a DataGrid. Grid is an area that contains other controls while DataGrid Represents a control that displays data in a tabular form. Looking at your code sample, I think DataGrid is what you wanted.
Assuming you did really mean Grid, then you can move your Button out by placing the entire Grid in another container (e.g. a DockPanel) like this:
<DockPanel>
<Button DockPanel.Dock="Bottom" Content="Add a new Customer" Height="100" Width="139"/>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="300" />
<ColumnDefinition Width="300" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="40" />
<RowDefinition Height="40" />
</Grid.RowDefinitions>
<Button FontWeight="Bold">Customer name</Button>
<Button Grid.Column="1" FontWeight="Bold">Name</Button>
<Label Grid.Row="1"></Label>
<Label Grid.Column="1" Grid.Row="1"></Label>
</Grid>
</DockPanel>