Mateusz Paprocki

This was supposed to be possible after PR #11949, but it needs a little more attention.

btw. `.gitignore` is currently badly set up (after PR #12368), which means you have to use `git add -f path_to.png`.

> `Error: unknown property panel.models.location.Location.reload` This required change from, e.g.: ```ts static init_SomeModel {} ``` to ```ts static {} ``` (see 9698782).

> (...) `plot_*`, which I think should be updated to `outer_*`. No, `plot_width` -> `width`. `outer_width` is a computed readonly value of actual `width`, as computed by the layout.

> `assert [{'attr': 'te..., 'new': '1'}] == [{'attr': 'te...'1881'}, ...}]` You should run pytest with `-vv`. However, I'm pretty sure it's just `old` that needs to be removed (or something...

> `standalone_docs_json_and_render_items()` takes 1 positional argument but 2 were given `suppress_callback_warning` is now a keyword only argument.

> `panel.models.comm_manager.CommManager(1002).plot_id` is unset Given this definition: ```py plot_id = String() ``` ```ts plot_id: p.Property ``` ```ts plot_id: [ String ], ``` the behavior is correct. Bokeh's properties don't allow...

> `plot_id = Nullable(String)` The intrinsic default is `None` for this type.

To create a required (no default value) nullable property, use: ```py plot_id = Required(Nullable(String)) ``` Unless `plot_id` is explicitly set, there will be a runtime exception whenever `plot_id` is accessed,...

> Is it correct to use initialize? That's the only way. If inheriting from `HasProps`, one should not touch the constructor. This constructor stub is only there for type purpose,...