Grid Column changing Width when animating - wpf

Question

I have a Grid element that has two columns and three rows. The last row has a height of 0... and I animate the height property using a custom animation class because the gridheight property isnt an integer..
The animation works just fine, but when I activate it, it changes the width of the second column seemingly randomly.. sometimes just a few pixels bigger and sometimes over double as wide...
Here is the grid code
<Grid >
<Grid.ColumnDefinitions>
<ColumnDefinition />
<ColumnDefinition Width="50"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="1*" />
<RowDefinition Height="7"/>
<RowDefinition Name="LyricsRow" Height="1">
<RowDefinition.Style>
<Style>
<Style.Triggers>
<DataTrigger Binding="{Binding Path=IsTrayOpen}" Value="True">
<DataTrigger.EnterActions>
<BeginStoryboard>
<Storyboard>
<local:GridLengthAnimation
Storyboard.TargetProperty="Height"
From="0" To="150" Duration="0:0:0.3" >
</local:GridLengthAnimation>
</Storyboard>
</BeginStoryboard>
</DataTrigger.EnterActions>
<DataTrigger.ExitActions>
<BeginStoryboard>
<Storyboard>
<local:GridLengthAnimation
Storyboard.TargetProperty="Height"
From="150" To="0" Duration="0:0:0.5" />
</Storyboard>
</BeginStoryboard>
</DataTrigger.ExitActions>
</DataTrigger>
</Style.Triggers>
</Style>
</RowDefinition.Style>
</RowDefinition>
</Grid.RowDefinitions>
Is there any reasons this could be going on?

Answer 1

For those of you that might be wondering about the GridLengthAnimation implementation mentioned in the question, here is one (from http://social.msdn.microsoft.com/forums/en-US/wpf/thread/da47a4b8-4d39-4d6e-a570-7dbe51a842e4/)
/// <summary>
/// Animates a grid length value just like the DoubleAnimation animates a double value
/// </summary>
public class GridLengthAnimation : AnimationTimeline
{
/// <summary>
/// Returns the type of object to animate
/// </summary>
public override Type TargetPropertyType
{
get
{
return typeof(GridLength);
}
}
/// <summary>
/// Creates an instance of the animation object
/// </summary>
/// <returns>Returns the instance of the GridLengthAnimation</returns>
protected override System.Windows.Freezable CreateInstanceCore()
{
return new GridLengthAnimation();
}
/// <summary>
/// Dependency property for the From property
/// </summary>
public static readonly DependencyProperty FromProperty = DependencyProperty.Register("From", typeof(GridLength),
typeof(GridLengthAnimation));
/// <summary>
/// CLR Wrapper for the From depenendency property
/// </summary>
public GridLength From
{
get
{
return (GridLength)GetValue(GridLengthAnimation.FromProperty);
}
set
{
SetValue(GridLengthAnimation.FromProperty, value);
}
}
/// <summary>
/// Dependency property for the To property
/// </summary>
public static readonly DependencyProperty ToProperty = DependencyProperty.Register("To", typeof(GridLength),
typeof(GridLengthAnimation));
/// <summary>
/// CLR Wrapper for the To property
/// </summary>
public GridLength To
{
get
{
return (GridLength)GetValue(GridLengthAnimation.ToProperty);
}
set
{
SetValue(GridLengthAnimation.ToProperty, value);
}
}
/// <summary>
/// Animates the grid let set
/// </summary>
/// <param name="defaultOriginValue">The original value to animate</param>
/// <param name="defaultDestinationValue">The final value</param>
/// <param name="animationClock">The animation clock (timer)</param>
/// <returns>Returns the new grid length to set</returns>
public override object GetCurrentValue(object defaultOriginValue,
object defaultDestinationValue, AnimationClock animationClock)
{
double fromVal = ((GridLength)GetValue(GridLengthAnimation.FromProperty)).Value;
//check that from was set from the caller
if (fromVal == 1)
//set the from as the actual value
fromVal = ((GridLength)defaultDestinationValue).Value;
double toVal = ((GridLength)GetValue(GridLengthAnimation.ToProperty)).Value;
if (fromVal > toVal)
return new GridLength((1 - animationClock.CurrentProgress.Value) * (fromVal - toVal) + toVal, GridUnitType.Star);
else
return new GridLength(animationClock.CurrentProgress.Value * (toVal - fromVal) + fromVal, GridUnitType.Star);
}
}

Answer 2

It probably depends on the content of the "cells"
try setting MaxWidth="50" on your columnDefinition in addition to Width="50"