In some places (e.g. stories from call centers on /r/TalesFromTechSupport), I’ve seen the term “I’m showing (some text/output)…” – apparently as a synonym for “I’m seeing/I’m being shown/it’s showing me…”. Is that interpretation correct, and where did this term come from? It sounds foreign but is used also by people who otherwise seem to be (mostly) native English speakers, and it’s one of the weirdest phrases I’ve read so far…
Interestingly, the etymology of the word comes from Old English sceawian "to look at, see, gaze...". So the question seems to be not when did the term come to mean "seeing" instead of "exhibit" but rather the reverse, when did the term change to mean "exhibit" which is our common modern day understanding? According to etymonline.com this occurred about 1200 "for unknown reasons and is unique to English (German schauen still means "look at)".
It would be interesting to know if the usage you describe is more prominent among German/English speakers.
"I'm showing ..." is simply a shortcut way of saying "My computer is showing ..."
This reflects the natural tendency of people to develop "shorthand" expressions for phrases that they use frequently. There are no deep, dark secrets hidden in its etymology.