I have seen a windows app with a text field whose max character count was somehow determined by system font size - probably a crude way to make sure the entered text fits the hard-coded field size.
The problem was that this field was used to enter a 10-digit code, and as it turns out, on default Windows10 system, the fonts are set up so that this field only fit 8 of them. Oops! :)
I'd like to see how that App would work with me sitting here fonts cranked up to 175%. I've never heard of a setup like that though - it sounds like it'd be surprisingly intricate to actually configure.
The problem was that this field was used to enter a 10-digit code, and as it turns out, on default Windows10 system, the fonts are set up so that this field only fit 8 of them. Oops! :)