"Visible on screen" unfortunately is a hard thing to determine. You can easily imagine a textbox with white text on a white background, or a very small textbox, or a textbox that briefly pops up whenever you type a keystroke or click the mouse, or...
Browsers really need to support some mechanism where the user can determine precisely what information will be filled prior to it being handed over to the website. This needn't be difficult; Chrome's existing autofill popup already displays a subset of the information, the popup just needs to give a fuller picture.
Browsers really need to support some mechanism where the user can determine precisely what information will be filled prior to it being handed over to the website. This needn't be difficult; Chrome's existing autofill popup already displays a subset of the information, the popup just needs to give a fuller picture.