Window preview is not displayed in the taskbar

[JustPilz]

Describe the bug
Window preview is not displayed in the taskbar with transparent: "true":

{
      "borderless": true/false,
      "transparent": true,
}

Also I tried other combinations:

1. "borderless": false and "transparent": false. It's correct.
   

2. "borderless": true and "transparent": false. It's correct too.
   

To Reproduce
Steps to reproduce the behavior:

1. Set modes.window.transparent to true in neutralino.config.json
2. npm run dev or build app

Expected behavior
The window preview should display correctly

Specifications

• OS: Windows 10 x64
• Neutralinojs version: v5.6.0
• Neutralinojs client library version: v5.6.0
• Neutralinojs CLI version: v11.3.1