I had not even thought of doing this, it's brilliant. I often run into this issue with my mother when I visit, even though I am her adult son. I will certainly try this.
Anyway, for people from Poland who might find the essay useful, here's the translation: http://esejepg.pl/eseje/makersschedule.html. There are also some others (in particular, I wanted to have "What You'll Wish You'd Known" available too, to show to my younger siblings).
(I'd also love to get some help with translating more of the essays. After some personal issues back some 4 years ago I lost the drive to continue the work; since then, however, I've been told those translations are actually being printed out and given to people in some business classes, which sounds like they're useful to someone.)
The remark in parenthesis is pretty important here. A lot of people seem to feel entitled to your full and immediate attention 24/7 just because they're family or know you for a while. I suppose GP feels that too ("what, you think you're so important that you can brush me off just like that, and I'm not even worthy being given a reason?"). There's this strange phenomenon when people in some sort of relationship start treating the other party with less respect they'd show to a stranger.
I spent a lot of my late-teen / young-adult years teaching people around me that yes, I'm always open to help, but if you want me to consider your request, please respect my time and focus - it'll be better for both of us. I even translated PG's "Maker's Schedule, Manager's Schedule" just so I could show it to my mom (and some other) in order to explain why I don't respond well to being asked to do trivial errands at random times during the day.
At work I simplify this - when I want to signal I'm concentrating, I just put on over-the-ear headphones.
And mind you - I'm probably one of the more accommodating person you'd met. I find it very hard to say "no" when people ask me for help nicely. What I wrote above is the result of dealing with years of frustration and eventually deciding it's too much.