Add isShown to TypeScript annotations

[CodeF53]

Is your feature request related to a problem? Please describe.
I use the isShown attribute of my viewer to disable my programs hotkeys while the viewer is open:

function hotkey(e: KeyboardEvent) {
  // disable hotkeys while viewer is open
  if (viewer.isShown)
    return

  const { key, ctrlKey, shiftKey } = e
  ...

But typescript thinks isShown isn't a value on viewer, despite it being one.

Property 'isShown' does not exist on type 'Viewer'

Describe the solution you'd like
When it comes to variables that could be useful to people, like isShown add them to TypeScript annotations

Describe alternatives you've considered
If you don't want people writing to them, mark them private and add getters so we can still use them in a readonly manner (ie: getIsShown())

[fengyuanchen]

The isShown property of the viewer instance is an internal property, not a public property. If you still want to use it, try (viewer as any).isShown please.

[CodeF53]

Can you give a good reason for why you can't give us a getter like getIsShown()?

as any is severe malpractice.

[CodeF53]

Can you give a good reason for why you can't give us a getter like getIsShown()?

as any is severe malpractice.

@fengyuanchen

[fengyuanchen]

There are too many internal properties (about 30). I don't think it is a good idea to expose any one of them as they may be changed later.