I experienced this with the “Upload Files” activity, but I bet it happens with any other else in Studio.
I have my zoom at 75%. I was typing something into one of the textinput boxes of the activity; then I noticed the blinking cursor was not there, which is very annoying. I pressed CTRL+plus to zoom in back to 100%… And guess what happened. Instead of increasing the size of the general view… it started zooming the size of the letter inside the textbox
. D’oh.