Windows 10: transparent icon bug in thumbnail preview

Question

I always had this bug, at least since I started using Windows 10 when it came out (I am now using version 1709, it's still there).

I think the thumbnail preview for certain transparent icon is broken. Specifically, I am talking about the notepad icon:

Example a is a folder with an .srt file (in my PC this type of file is opened with notepad, so it automatically gets that icon). I've copied the same file outside the folder to show you it's not a broken icon. Notice the red/green artifact in the preview, where the transparent part of the icon should be.

Example b is the same, but with two .srt files inside the folder. The icons in the previews are tilted, so the transparent part is hidden.

I've unsuccessfully tried to reproduce this bug with other icons. At most, what I obtained was a partial transparent icon, not coloured artifacts, like in this second image:

So, am I missing something? Some graphic/performance options I do not know of?

Answer 1

I can confirm the issue exists and is reproducible in Windows 10.

It appears to be a bug in the thumbnail code for Windows. I've used IconExtract to review the icons in notepad.exe and don't see any problem within them.

The code that renders the thumbnail inside the folder image appears to have a bug.

I'm not sure what other answer to provide.

I would recommend submitting the details of this bug through the Microsoft Feedback Hub.

Steps to reproduce:

• Create a test folder
• Within the test folder, create another folder the folder.
• Within the folder folder, right-click and create a New Text Document.
• Give the new file a name and change the file extension of the New Text Document to a random extension. I used new text document.srt.
• Try to open the new text document.srt file you created and Windows will prompt for which program to open it with. Choose to always open with Notepad.exe.
• Change your folder view to Large, or Extra Large icons. Observe that the new text document.srt file displays the notepad thumbnail properly.
• Navigate up to the test folder and change your view to Large, or Extra Large icons. Observe that the notepad thumbnail is not displayed properly for the folder thumbnail.