problem with font size in WPF

Question

Hi, im programming with c#, and im doing one form using WPF, and i need show texts on it. Im using code below to draw text, but font size appears smaller than size indicated (i defined as arial 160, and appears about 118). I dont know what im doing bad, somebody can help me please. Also, over text appears a space, i want that text starts at heigh indicated in texbox position not below; you can see small line as texbox container.

 

thanks a lot.

TextBox textBox = new TextBox();
textBox.BorderThickness = new Thickness(1);
textBox.IsHitTestVisible = false;
textBox.Focusable = false;
textBox.TextWrapping = TextWrapping.WrapWithOverflow;
textBox.VerticalScrollBarVisibility = ScrollBarVisibility.Hidden;
textBox.HorizontalScrollBarVisibility = ScrollBarVisibility.Hidden;
textBox.Tag = (object)mText.Id;
textBox.Text = mText.Text;
textBox.FontSize = mText.Size;
textBox.Foreground = XDisplay.ConvertStringColorToBrush(mText.Color);
textBox.Background = XDisplay.ConvertStringColorToBrush(mText.BackgroundColor);
textBox.FontFamily = new FontFamily(mText.FontName);
textBox.FontWeight = mText.Bold ? FontWeights.Bold : FontWeights.Normal;
textBox.FontStyle = mText.Italic ? FontStyles.Italic : FontStyles.Normal;
textBox.Opacity = mText.Opacity;
textBox.Width = mText.Width;
textBox.Height = mText.Height;
textBox.TextAlignment = (TextAlignment)mText.Alignment;
Canvas.SetTop(textBox, mText.Y);
Canvas.SetLeft(textBox, mText.X);
Panel.SetZIndex(textBox, mText.Layer);
return textBox;