How to Make Window Semi-Transparent Automatically While It's under the Mouse Pointer
Create specific settings for the desired target window.
Go to the Transparency property sheet of just created settings.
In the Make Window Transparent Automatically group mark the While mouse-hovering check box.
Set the desired transparency level.Note
Target window's transparency will be reset automatically to its previous value when you move the mouse pointer outside window's bounds.
Apply your adjustments.