WPF/XAML/C# Setting a Boolean variable on MouseOver - wpf

Question

If I have a boolean variable in a ViewModel Class, lets say
public bool test = true; (This is in C#)
Is there ANYWAY in XAML/Expression Blend to take this variable and change it to
false USING PURELY XAML, no code behind or anything?
I want to do this for a mouse over event.
If the mouse is over a certain object the boolean variable should become false, otherwise it should remain true.

Answer 1

Answer 1 (easiest):
Why not do this?
public bool Test
{
get { return myControl.IsMouseOver; }
}
I know you want to do it in all XAML, but since you're already declaring the property, you might as well do this instead of saying.
public bool Test = false;
Answer 2 (more code, MVVM approach which is better in the long run):
Here basically, you create a Dependency Property (called Test) on Window1, and on the XAML side, you create a style for Window1 that says that its Test property will be the same as the button IsMouseOver property (I left the myButton_MouseEnter event so you can check the state of the variable when the mouse is over the button, I checked myself and it does change to true, you can remove the MouseEnter handler, and it'll still work)
XAML:
<Window x:Class="StackOverflowTests.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Window1" x:Name="window1" Height="300" Width="300"
xmlns:local="clr-namespace:StackOverflowTests">
<Window.Resources>
<Style TargetType="{x:Type local:Window1}">
<Setter Property="Test" Value="{Binding ElementName=myButton, Path=IsMouseOver}">
</Setter>
</Style>
</Window.Resources>
<Grid>
<Button x:Name="myButton" Height="100" Width="100" MouseEnter="myButton_MouseEnter">
Hover over me
</Button>
</Grid>
</Window>
C#:
public partial class Window1 : Window
{
public Window1()
{
InitializeComponent();
}
public bool Test
{
get { return (bool)GetValue(TestProperty); }
set { SetValue(TestProperty, value); }
}
// Using a DependencyProperty as the backing store for Test. This enables animation, styling, binding, etc...
public static readonly DependencyProperty TestProperty =
DependencyProperty.Register("Test", typeof(bool), typeof(Window1), new UIPropertyMetadata(false));
private void myButton_MouseEnter(object sender, MouseEventArgs e)
{
bool check = this.Test;
}
}