Hi,

I met an issue while I was using xhb. When a certain property of root window being changed, it was supposed to give me an AccessError. But actually I got "thread blocked indefinitely in an STM transaction" when I waitForEvent.

AFAIK, in xhb, it forks a thread to read what X server sends. Then parse and put it into a TChan. waitForEvent reads from the TChan.

It is reasonable to me that if X server did not send anything, then waitForEvent would be blocked. But apparently there are some other policies in RTS.

So what is that? And how should I debug it?

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