I have always just used the PrtSc (Print Screen) button on my keyboard, then just pasted to paint and save as png, works on every software you can minimize, and on every windows OS*. My Venetica install doesn't always like to be minimized though, so I'd recommend saving before minimizing, however Venetica has a few incompatibilities with my system it seems, and I have rarely had such problems with other softwares. This takes a moment, but I always know it worked, and where the file is. I do this with Win98SE, and with Win10. I often do this when I need to piece together multiple parts of a page, or pages, such as the product descriptions and images from one page and the price readout from another. It also means I don't have to worry about a window within a window, or other oddities.
Alternatively, drop box used to be able to be setup to automatically download any screen cap you make with PrtSc, and I don't see why they'd discontinue that feature.
*Not sure about Windows 3.1 or non GUI Windows OS such as DOS 6.22.
Post edited March 30, 2020 by Scrapack