Dash

Changed
- [1376](https://github.com/plotly/dash/pull/1376) Extends the `getTransform` logic in the renderer to handle `persistenceTransforms` for both nested and non-nested persisted props. This was used to to fix [dcc#700](https://github.com/plotly/dash-core-components/issues/700) in conjunction with [dcc#854](https://github.com/plotly/dash-core-components/pull/854) by using persistenceTransforms to strip the time part of the datetime so that datepickers can persist when defined in callbacks.

Fixed
- [1408](https://github.com/plotly/dash/pull/1408) Fixes a bug where the callback graph layout would reset whenever a callback fired, losing user-initiated layout changes ([#1402](https://github.com/plotly/dash/issues/1402)) or creating a new force layout ([#1401](https://github.com/plotly/dash/issues/1401))

Added
- [1371](https://github.com/plotly/dash/pull/1371) You can now get [CSP `script-src` hashes](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy/script-src) of all added inline scripts by calling `app.csp_hashes()` (both Dash internal inline scripts, and those added with `app.clientside_callback`) .

Changed
- [1385](https://github.com/plotly/dash/pull/1385) Closes [#1350](https://github.com/plotly/dash/issues/1350) and fixes a previously undefined callback behavior when multiple elements are stacked on top of one another and their `n_clicks` props are used as inputs of the same callback. The callback will now trigger once with all the triggered `n_clicks` props changes.
- [1179](https://github.com/plotly/dash/pull/1179) New and improved callback graph in the debug menu. Now based on Cytoscape for much more interactivity, plus callback profiling including number of calls, fine-grained time information, bytes sent and received, and more. You can even add custom timing information on the server with `callback_context.record_timing(name, seconds)`

Fixed
- [1384](https://github.com/plotly/dash/pull/1384) Fixed a bug introduced by [#1180](https://github.com/plotly/dash/pull/1180) breaking use of `prevent_initial_call` as a positional arg in callback definitions

Added
- [1355](https://github.com/plotly/dash/pull/1355) Removed redundant log message and consolidated logger initialization. You can now control the log level - for example suppress informational messages from Dash with `app.logger.setLevel(logging.WARNING)`.
- [1253](https://github.com/plotly/dash/pull/1253), [#1377](https://github.com/plotly/dash/pull/1377) Added experimental `--jl-prefix` option to `dash-generate-components`, optionally generates Julia version of components and corresponding Julia package

Changed
- [1180](https://github.com/plotly/dash/pull/1180) and [#1375](https://github.com/plotly/dash/pull/1375) `Input`, `Output`, and `State` in callback definitions don't need to be in lists. You still need to provide `Output` items first, then `Input` items, then `State`, and the list form is still supported. In particular, if you want to return a single output item wrapped in a length-1 list, you should still wrap the `Output` in a list. This can be useful for procedurally-generated callbacks.
- [1368](https://github.com/plotly/dash/pull/1368) Updated pytest to v6.0.1. To avoid deprecation warnings, this also updated pytest-sugar to 0.9.4 and pytest-mock to 3.2.0. The pytest-mock update only effects python >= 3.0. Pytest-mock remains pinned at 2.0.0 for python == 2.7.

Added
- [1343](https://github.com/plotly/dash/pull/1343) Add `title` parameter to set the
document title. This is the recommended alternative to setting app.title or overriding
the index HTML.
- [1315](https://github.com/plotly/dash/pull/1315) Add `update_title` parameter to set or disable the "Updating...." document title during updates. Closes [#856](https://github.com/plotly/dash/issues/856) and [#732](https://github.com/plotly/dash/issues/732)

Fixed
- [1310](https://github.com/plotly/dash/pull/1310) Fix a regression since 1.13.0 preventing more than one loading state from being shown at a time.