Button width is not stretch - wpf

Question

I try to use the metro style from MahApps but buttons becomes not "SizeToContent" or becomes not AutoResized or something like that.
This is my button style
<Style x:Key="GrayMetroButtonStyle" TargetType="Button" BasedOn="{StaticResource LightMetroWindowButtonStyle}">
<Setter Property="Margin" Value="5"/>
<Setter Property="Background" Value="LightGray"/>
<Setter Property="Padding" Value="2"/>
</Style>
This is the style using in WPF. The width of the button's column is larger than the button needed to check autoresize.
<Grid Grid.Row="0">
<Grid.ColumnDefinitions>
<ColumnDefinition/>
<ColumnDefinition Width="80" />
</Grid.ColumnDefinitions>
<TextBlock Grid.Column="0" VerticalAlignment="Center" HorizontalAlignment="Left" Text="{Binding ManifestFileName}" Margin="5" />
<Button Grid.Column="1" Content="Change" Margin="2" Visibility="{Binding LoadButtonVisibility}" Command="{Binding LoadManifest}" Style="{StaticResource GrayMetroButtonStyle}" />
</Grid>
And result is
As you see, content is out of the buttons width range.
If i clear the style refference, button get a properly behavior.
Which property are rule this behavior? How can i make this buttons autoresizable?
Thanks for replies.

Answer 1

According to the comments in the MahApps sources, LightMetroWindowButtonStyle is intended for the minimize, maximize, and close buttons in the title bar of a Metro-style window. For that reason, the style sets a fixed Width of 34.
It looks like the 'standard' button style for MahApps is MahApps.Metro.Styles.MetroButton, so I would suggest using that instead. It actually looks like this is the style that gets applied by default, as the second image you posted (the button with the style cleared) looks like it has this style already applied.
There are others too, like SquareButtonStyle and AccentedSquareButtonStyle, which are showcased in the MahApps example app:
If you want the 'flat' look, MetroFlatButton looks pretty similar to the button in the first image. You can see the various MahApps button styles in the MahApps docs and see the actual source code on GitHub .
Note that some of the button styles force their content to display in lowercase. If you want to avoid this, you can extend one of the MahApps styles and override a single property, e.g.:
<Style x:Key="SquareButtonStyleNormalCase"
BasedOn="{StaticResource SquareButtonStyle}"
TargetType="Button">
<Setter Property="m:ControlsHelper.ContentCharacterCasing"
Value="Normal" />
</Style>