LogForegroundWindow

If a suspicious application window or dialog box is often displayed on your desktop, and you can’t figure out what its purpose is, LogForegroundWindow is an application that could help you out.
This program logs each window that comes into focus, even if just for a split second. It records every available detail, making it easier to identify and remove potentially unwanted software, but it may also come in handy in other situations.

Keep track of all foreground windows

Once launched, LogForegroundWindow begins monitoring your desktop automatically, and you can fine-tune the poll interval to control how often the application should perform a check.
When a certain window is displayed in the foreground, the utility records its details, as well as the current time. It captures the window's name, class, position, PID, executable path and many other attributes.

Features an outdated UI and lacks a couple of useful functions

As far as looks are concerned, the application is quite clearly out of date, but this may not be a big issue for users who just need to identify a certain window quickly.
However, we would have liked to be able to pause the scanning process and export the entire log at once. Currently, you can only copy the contents of a single cell or line to the clipboard, and the log is deleted automatically when shutting down the program.

Lightweight design and simple deployment procedure

LogForegroundWindow uses up very little disk space, and its resource impact is minimal. Because it is a portable application, you can even place it on a portable storage drive and run it on any PC without going through an installation procedure beforehand.
Overall, this is a straightforward and simple-to-use piece of software that enables you to monitor foreground windows continuously and record their details. It could be improved in a couple of respects, but it is a lightweight and portable app that can be useful in many situations.