ATTEMPTED RACIAL INTIMIDATION
Because she was standing over my left shoulder while I was still using the computer, she was obviously expecting me to move out of her way immediately - even though she could clearly see that my session had not yet ended.
She never claimed she was to use the PC after me, so her basic assumption was that I was somehow in her way - right there and then - with no right to be. (Hear relevant 45-second audio.)
I continued working and, even after I requested she stop looking over my shoulder, she persisted in doing so. This - and her needless interruption - made me lose concentration and provoke my anger.
I never see Whites interrupt other Whites in the library to tell them that they are using any PC after them, because queuing is largely understood as a concept and a practice in the UK and so Whites (rightly) would not tolerate such behaviour.
Racist Whites believe that Black people must step out of their way - without question - simply because the former assume an automatic right-of-way over non-Whites - in public. They also believe that waiting ones turn in a queue is unnecessary when a Black man is in front of them.