Added app.beep() to play the default system notification sound.

[bruno-rino]

app.beep() is a new method that will play the default system notification sound.

Only tested for macOS

PR Checklist:

• All new features have been tested
• All new features have been documented
• I have read the CONTRIBUTING.md file
• I will abide by the code of conduct

API References:

• https://developer.apple.com/documentation/appkit/1473622-nsbeep
• https://docs.gtk.org/gdk3/func.beep.html
• https://learn.microsoft.com/en-us/dotnet/desktop/winforms/controls/how-to-play-a-beep-from-a-windows-form

[freakboy3742]

So... this seems like a reasonable implementation of a fairly straightforward feature, but I have to ask... Why?

[bruno-rino]

I'm working on a minimal example for a DocumentApp. It doesn't support opening the same file in separate windows, so if I try to open a file a second time, I want to give some non intrusive feedback. I think beep is the standard way to do that.

[freakboy3742]

I'm not sure I agree that a beep is the right error output for something like loading a document twice - or, if it is, it's something that should be done in conjunction with other forms of feedback (like a dialog). I would have thought this was something that the operating system would have enforced with it's own APIs, rather than being something that an end-user needed to code explicitly.

However, I can't argue that the API exists on pretty much every platform, and it's a fairly small API, so I guess it can't hurt to add it.