Meaning of "About not very much."

Question

From the book 100-year-old man who climbed out the window and disappeared.

"Allan was beginning to tire of Stalin's touchness. The old geezer was quite red in the face with anger , but about not very much. Stalin went on ."

From the above sentence what does 'about not very much mean'?

Thanks in advance.

Answer 1

If a situation or general thing is causing you to feel angry, you can say you are angry about it.

I am angry about losing the game.

In the example sentence, the writer is saying Stalin was angry, but about something that is not very much, meaning something minor or trivial.