New Post: How to chnage install directory from WPF Application

I am working on bootstrapper UI as my benchmark and created new UI in WPF.
When the "Install Directory " property is changed ,I have added it in Static variables so that it can be accessed in setup.cs file.
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Here Data variables is my static Class .I filled the values in the main screen .
But Msi file is created before user filling values.

It will be beneficial to many users as lots of user required this functionality.
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static public void Main(string[] args)
{

System.Windows.Forms.MessageBox.Show(DataVariables.installationFolder);


var productProj =
    new Project("My Product",
        new Dir(DataVariables.installationFolder +@"\My Company\My Product",
            new File("readme.txt")
            )
            ) { InstallScope = InstallScope.perMachine };
productProj.GUID = new Guid("6f330b47-2577-43ad-9095-1861bb258778");
string productMsi = productProj.BuildMsi();

//------------------------------------
var bootstrapper =
        new Bundle("My Product",                    
            new MsiPackage(productMsi) { Id = "MyProductPackageId", DisplayInternalUI = false });

System.Windows.Forms.MessageBox.Show(System.Reflection.Assembly.GetExecutingAssembly().Location.ToString());
bootstrapper.Version = new Version("1.0.0.0");
bootstrapper.UpgradeCode = new Guid("6f330b47-2577-43ad-9095-1861bb25889a");
bootstrapper.Application = new ManagedBootstrapperApplication("%this%"); // you can also use System.Reflection.Assembly.GetExecutingAssembly().Location
bootstrapper.PreserveTempFiles = true;
bootstrapper.Build();    
io.File.Delete(productMsi);

}