This program is an example of using matplotlib library to make graphs with hover labels and uses PyQt5 backend for the GUI. It was difficult coming up with hover labels for matplotlib that would work ...
X-ray data is frequently plotted on an energy scale in log format. At the same time, the energy range of common detectors is only about one order of magnitude (e.g. Chandra ACIS .4 - 10 keV, XMM EPIC ...