/usr/bin/xwininfo, xwininfo
Explanation:
The command that can be used to investigate the properties for a particular window in X by clicking that window is xwininfo. xwininfo is a command-line tool that provides information about X windows. When executed, it opens a small window and waits for the user to select a window by clicking on it. Then, it displays various characteristics about the window in question, such as its geometry, position, size, depth, class, name, id, and more. xwininfo is part of the X Window System, which is a graphical user interface system for Unix-like operating systems. xwininfo can be useful for debugging, testing, or scripting purposes. References:
https://bing.com/search?q=command+to+investigate+properties+of+a+window+in+X
https://www.exam-answer.com/linux-foundation-certified-system-administrator-lfcs-simulation-investigate-wind