What computer accessory was the result of the work on human-computer interaction by the creator of hypertext?  
Purple Numbers: Purple Numbers is a suite of tools that allows one to address paragraphs of HTML content. Purple Numbers:  It was originally conceived by Douglas Engelbart for his creation of hypertext. Douglas Engelbart:  He is best known for his work on founding the field of human–computer interaction, particularly while at his Augmentation Research Center Lab in SRI International, which resulted in creation of the computer mouse, and the development of hypertext, networked computers, and precursors to graphical user interfaces.
i don't know