[Rendering] Non transparent background when containers use select action

[Diegorro98]

Target Platforms

UWP, specifically WinUI 3

SDK Version

Unknown, I'm seeing this at the Widget board, I tried to see the version at AdaptiveCards.Rendering.WinUI3.dll detailed properties but is empty, version of the Widgets board is 524.34401.0.0

Application Name

Widgets board

Problem Description

When setting selectAction inside a container element (such Container itself or Column) the background becomes non transparent (near black at dark mode, white at light mode).

Screenshots

You can see it at the Phone Link widget, at clear all button (in this case "Borrar todo"), where there is a white background behind the letters:

Card JSON

{
    "type": "AdaptiveCard",
    "$schema": "http://adaptivecards.io/schemas/adaptive-card.json",
    "version": "1.6",
    "body": [
        {
            "type": "ColumnSet",
            "columns": [
                {
                    "type": "Column",
                    "width": "stretch",
                    "items": [
                        {
                            "type": "TextBlock",
                            "text": "Transparent",
                            "wrap": true
                        }
                    ]
                },
                {
                    "type": "Column",
                    "width": "stretch",
                    "items": [
                        {
                            "type": "TextBlock",
                            "text": "Non transparent",
                            "wrap": true
                        }
                    ],
                    "selectAction": {
                        "type": "Action.Execute"
                    }
                }
            ]
        }
    ]
}

Sample Code Language

No response

Sample Code

No response