ListBox history is not completely transparent

I have TabControl

one that contains ListBox

. I've set both Background controls to Transparent

, but the ListBox seems to have some sort of matte effect:

How can I get rid of this effect? The other controls in the TabControl have no problem when I set their background to Transparent, only the ListBox.

EDIT:

I found the problem. The problem is not with the ListBox, but with the SurfaceListBox. More details here .

For a solution add this to the resource:

<Window.Resources>
    <SolidColorBrush x:Key="{x:Static s:SurfaceColors.ListBoxBackgroundBrushKey}" Color="Transparent" />
</Window.Resources>