`PollEvent()` returns `nil` when screen is suspended

[rivo]

It seems that the behaviour of Screen.PollEvent() has changed with v2.7.0. Whereas before, PollEvent() blocked between a call to Screen.Suspend() and Screen.Resume(), now it returns with a nil value.

Was this change intended? The documentation says that PollEvent() "will return nil if the Screen is finalized" and I would not consider a suspended screen finalized. So I would expect PollEvent() to block until the next event is received, as it was before v2.7.0.

If this change was intended, I think it should be documented ("if the Screen is finalized or suspended"). Then (at least in tview) I would have to keep track of suspended states whereas now, I use the nil value solely to determine if a screen has been finalized. Personally, though, I would like this to go back to how it was before (i.e. PollEvent() blocks until the next event from an active screen).

Here's some code to reproduce this:

func main() {
	s, _ := tcell.NewScreen()
	s.Init()

	s.PollEvent()

	s.Suspend()
	s.PollEvent() // This returns with nil in v2.7.0. It blocks in v2.6.1.
	s.Resume()

	s.PollEvent()

	s.Fini()
}

[gdamore]

This was an unintentional change, and is a rightly a bug.

[rivo]

Thank you!

[ilikeorangutans]

Thanks so much for fixing this! ❤️