How to disable taskbar preview thumbnails in Windows 10

In Windows 10, when you hover over a taskbar button of a running app or group of apps, a thumbnail preview appears on the screen. For a single window it shows a single thumbnail, and for multiple windows it shows a number of thumbnail previews in a row. If you wish to disable these thumbnails in Windows 10, I will explain how it can be done with a simple Registry tweak.

To disable taskbar preview thumbnails in Windows 10, do the following:

1. Open Registry Editor.
2. Go to the following Registry key:

   HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced

   Tip: You can access any desired Registry key with one click.
3. Here, create a new 32-bit DWORD value named ExtendedUIHoverTime. Note: If you are running 64-bit Windows 10, you still need to create a 32-bit DWORD. Set its value data to 9000 in decimals. This means it will show the thumbnail after 9000 milliseconds (or 9 seconds) of hovering over any taskbar button. So, with such a high timeout value, you will never see taskbar thumbnail previews.
4. Restart the Explorer shell or sign out and sign in back to Windows 10.

This will disable taskbar thumbnail previews in Windows 10. See screenshots below.
Before:

After:
It is possible to disable taskbar thumbnails only for a group of opened windows i.e.multiple instances of the app. Once this is done, Windows 10 will show a list of windows instead of thumbnails. The list makes it easier to identify them from a group instead of mostly similar looking thumbnails. To do this, follow these instructions:

1. Go to the following Registry key:

   HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Taskband

2. Create a new 32-bit DWORD value named NumThumbnails. Leave its value as 0. Note: If you are running 64-bit Windows 10, you still need to create a 32-bit DWORD value.
3. Restart the Explorer shell or sign out and sign in back to Windows 10.

Or simply try this software

Winaero Tweaker

If you would like to avoid Registry editing, here is good news for you. In the past, I created a freeware tool called Winaero Tweaker, One of its options is "Taskbar Thumbnails". It can tweak and change many hidden secret taskbar thumbnail parameters which cannot be changed via the Windows 10 GUI.
It can control all mentioned parameters in the article and many more. Using this tool, you will be able:

• Adjust thumbnail size.
• Adjust number of grouped application thumbnail windows.
• Adjust horizontal spacing between the thumbnails.
• Adjust vertical spacing between the thumbnails.
• Adjust thumbnail's caption position.
• Adjust thumbnail's top margin.
• Adjust thumbnail's bottom margin.
• Adjust thumbnail's left margin.
• Adjust thumbnail's right margin.
• Completely disable taskbar thumbnails.

To run it in Windows 10, download Winaero Tweaker from here. It works in Windows 10, Windows 8 and Windows 7 without issues.