前臺控件中：

Width="{Binding RelativeSource={RelativeSource AncestorType=Window}, Path=Width}"

后臺代碼：

定義在加載事件里面this.SizeChanged += ProductData_SizeChanged;

private void ProductData_SizeChanged(object sender, SizeChangedEventArgs e)
{
CalculatedControlWidth(this.ActualWidth, this.ActualHeight);
}
private void CalculatedControlWidth(double windowWidth, double windowHeight)
{
double width = windowWidth;
double textBoxWidth = (width - 190) / 8.5;
productCode.Width = textBoxWidth;
typeCombox.Width = textBoxWidth;
double height = windowHeight;
dataGrid.Height = height - 232;
}