If you find that the time you have to hover the mouse pointer over the taskbar icon, to preview the taskbar thumbnails, too much, you can make them appear faster in Windows 7.
Make Taskbar Previews appear faster
Open regedit and navigate to the following registry key:
HKEY_CURRENT_USER Control Panel Mouse
In the right pane, right-click MouseHoverTime. Select Modify. The default value is 400 ms. Set the new value at, say, 100.
Click OK. Exit regedit. Reboot.
You will find that when you hover, taskbar previews appear much faster.
Incidentally, MouseHoverTime indicates the amount of time, in milliseconds, that a right mouse pointer is within an area of the size of the MouseHoverSize property to generate a hover notification.
Meanwhile, MouseHoverSize indicates the size of the rectangle in which the right mouse pointer stays with the mouse hover time before the mouse’s hover notification is generated. You can see that all of these including height & width can be changed here.
Note that MouseHoverTime will customize the hover time globally, as it adjusts the delay for everything, including tooltips, taskbar icons, start menu, and more.
I liked having faster previews, tooltips etc., so suggested this.
If you want to customize the Taskbar Preview Thumbnail Hover Delay, then, INSTEAD, just add a new DWORD named “ ExtendedUIHoverTime ” and give it a value of 100.