Instant ThumbView is a tiny image viewer that displays image thumbnails in a tooltip window, when mouse pointer is hovered over an image file in Windows Explorer. It supports a lot of popular image file formats, including BMP, GIF, JPEG, PNG, WMF, EMF, TIFF and is very handy for quick image viewing.
To bring it up, open any folder with image files in Windows Explorer, and then hover an image file with your mouse pointer.
Instant ThumbView displays the thumbnail of selected image file in a popup window just next to the mouse pointer.
To adjust thumbnail dimensions, set displaying options and select image file formats use its Configuration Manager.
This software is a shareware. You will be able to download and test Instant ThumbView during a certain period of time, then, if it does what you need, you will have to acquire the full version from Instant ThumbView publisher. The Instant ThumbView 1.8.6 free trial version contains an installer and an uninstaller, and has a size of 778 Kilobytes.
For additional information and support request, please contact directly Instant ThumbView publisher.

Instant ThumbView Screenshot