To see the full list of pull requests and issues, see the [7.0 milestone](https://github.com/jupyter-widgets/ipywidgets/milestone/12?closed=1) on GitHub.
Major user-visible changes in ipywidgets 7.0 include:
- Widgets are now displayed in the output area in the classic notebook and are treated as any other output. This allows the widgets to work more naturally with other cell output. To delete a widget, clear the output from the cell. Output from functions triggered by a widget view is appended to the output area that contains the widget view. This means that printed text will be appended to the output, and calling `clear_output()` will delete the entire output, including the widget view. ([1274](https://github.com/jupyter-widgets/ipywidgets/pull/1274), [#1353](https://github.com/jupyter-widgets/ipywidgets/pull/1353))
- Removed the version validation check since it was causing too many false warnings about the widget javascript not being installed or the wrong version number. It is now up to the user to ensure that the ipywidgets and widgetsnbextension packages are compatible. ([1219](https://github.com/jupyter-widgets/ipywidgets/pull/1219))
- The documentation theme is changed to the new standard Jupyter theme. ([1363](https://github.com/jupyter-widgets/ipywidgets/pull/1363))
- The `layout` and `style` traits can be set with a dictionary for convenience, which will automatically converted to a Layout or Style object, like `IntSlider(layout={'width': '100%'}, style={'handle_color': 'lightgreen'})`. ([1253](https://github.com/jupyter-widgets/ipywidgets/pull/1253))
- The Select widget now is a listbox instead of a dropdown, reverting back to the pre-6.0 behavior. ([1238](https://github.com/jupyter-widgets/ipywidgets/pull/1238))
- The Select and SelectMultiple widgets now have a `rows` attribute for the number of rows to display, consistent with the Textarea widget. The `layout.height` attribute overrides this to control the height of the widget. ([1250](https://github.com/jupyter-widgets/ipywidgets/pull/1250))
- Selection widgets (`Select`, `Dropdown`, `ToggleButtons`, etc.) have new `.value`, `.label`, and `.index` traits to make it easier to access or change the selected option. ([1262](https://github.com/jupyter-widgets/ipywidgets/pull/1262), [#1513](https://github.com/jupyter-widgets/ipywidgets/pull/1513))
- Selection container widgets (`Accordion`, `Tabs`) can have their `.selected_index` set to `None` to deselect all items. ([1495](https://github.com/jupyter-widgets/ipywidgets/pull/1495))
- The `Play` widget range is now inclusive (max value is max, instead of max-1), to be consistent with Sliders
- The `Play` widget now has an optional repeat toggle button (visible by default). ([1190](https://github.com/jupyter-widgets/ipywidgets/pull/1190))
- A refactoring of the text, slider, slider range, and progress widgets in resulted in the progress widgets losing their `step` attribute (which was previously ignored), and a number of these widgets changing their `_model_name` and/or `_view_name` attributes ([1290](https://github.com/jupyter-widgets/ipywidgets/pull/1290))
- The `Checkbox` description is now on the right of the checkbox and is clickable. The `Checkbox` widget has a new `indent` attribute (defaults to `True`) to line up nicely with controls that have descriptions. To make the checkbox align to the left, set `indent` to `False`. ([1346](https://github.com/jupyter-widgets/ipywidgets/pull/1346))
- A new Password widget, which behaves exactly like the Text widget, but hides the typed text: `Password()`. ([1310](https://github.com/jupyter-widgets/ipywidgets/pull/1310))
- A new SelectionRangeSlider widget for selecting ranges from ordered lists of objects. For example, this enables having a slider to select a date range. ([1356](https://github.com/jupyter-widgets/ipywidgets/pull/1356))
- The `Label` widget now has no width restriction. ([1269](https://github.com/jupyter-widgets/ipywidgets/pull/1269))
- The description width is now configurable with the `.style.description_width` attribute ([1376](https://github.com/jupyter-widgets/ipywidgets/pull/1376))
- ToggleButtons have a new `.style.button_width` attribute to set the CSS width of the buttons. Set this to `'initial'` to have buttons that individually size to the content width. ([1257](https://github.com/jupyter-widgets/ipywidgets/pull/1257))
- The `readout_format` attribute of number sliders now validates its argument. ([1550](https://github.com/jupyter-widgets/ipywidgets/pull/1550))
- The `IntRangeSlider` widget now has a `.readout_format` trait to control the formatting of the readout. ([1446](https://github.com/jupyter-widgets/ipywidgets/pull/1446))
- The `Text`, `Textarea`, `IntText`, `BoundedIntText`, `FloatText`, and `BoundedFloatText` widgets all gained a `continuous_update` attribute (defaults to `True` for `Text` and `TextArea`, and `False` for the others). ([1545](https://github.com/jupyter-widgets/ipywidgets/pull/1545))
- The `IntText`, `BoundedIntText`, `FloatText`, and `BoundedFloatText` widgets are now rendered as HTML number inputs, and have a `step` attribute that controls the resolution. ([1545](https://github.com/jupyter-widgets/ipywidgets/pull/1545))
- The `Text.on_submit` callback is deprecated; instead, set `continuous_update` to `False` and observe the `value` attribute: `mywidget.observe(callback, 'value')`. The `Textarea.scroll_to_bottom` method was removed. ([1545](https://github.com/jupyter-widgets/ipywidgets/pull/1545))
- The `msg_throttle` attribute on widgets is now gone, and the code has a hardcoded message throttle equivalent to `msg_throttle=1`. ([1557](https://github.com/jupyter-widgets/ipywidgets/pull/1557))
- Using function annotations to specify interact controls for a function is now deprecated and will be removed in a future version of ipywidgets. ([1292](https://github.com/jupyter-widgets/ipywidgets/pull/1292))
- There are now two simple ways to embed widgets in an HTML page: with a simple script tag that does not use require.js and does not support anything but the basic widgets, and a require module that does support custom widgets. See the migration guide for more details. ([1615](https://github.com/jupyter-widgets/ipywidgets/pull/1615), [#1629](https://github.com/jupyter-widgets/ipywidgets/pull/1629), [#1630](https://github.com/jupyter-widgets/ipywidgets/pull/1630))
If you are developing a custom widget or widget manager, here are some major changes that may affect you. The [migration guide](./migration_guides.md) also walks through how to upgrade a custom widget.
- On the Python/kernel side:
- The Python `register` decorator for widget classes no longer takes a string argument, but registers a widget class using the `_model_*` and `_view_*` traits in the class. Using the decorator as `register('name')` is deprecated and should be changed to just `register`. [1228](https://github.com/jupyter-widgets/ipywidgets/pull/1228), [#1276](https://github.com/jupyter-widgets/ipywidgets/pull/1276)
- Widgets will now need correct `_model_module` and `_view_module` Unicode traits defined.
- Selection widgets now sync the index of the selected item, rather than the label. ([1262](https://github.com/jupyter-widgets/ipywidgets/pull/1262))
- The Python `ipywidget.domwidget.LabeledWidget` is now `ipywidget.widget_description.DescriptionWidget`, and there is a new `ipywidget.widget_description.DescriptionStyle` that lets the user set the CSS width of the description.
- Custom serializers can now return a structure that contains binary objects (`memoryview`, `bytearray`, or Python 3 `bytes` object). In this case, the sync message will be a binary message, which is much more efficient for binary data than base64-encoding. The Image widget now uses this binary synchronization. ([1194](https://github.com/jupyter-widgets/ipywidgets/pull/1194), [#1595](https://github.com/jupyter-widgets/ipywidgets/pull/1595), [#1643](https://github.com/jupyter-widgets/ipywidgets/pull/1643))
- On the Javascript side:
- The `jupyter-js-widgets` Javascript package has been split into `jupyter-widgets/base` package (containing base widget classes, the DOM widget, and the associated layout and style classes), and the `jupyter-widgets/controls` package (containing the rest of the Jupyter widgets controls). Authors of custom widgets will need to update to depend on `jupyter-widgets/base` instead of `jupyter-js-widgets` (if you use a class from the controls package, you will also need to depend on `jupyter-widgets/controls`). See the [cookie cutter](https://github.com/jupyter-widgets/widget-cookiecutter) to generate a simple example custom widget using the new packages.
- Custom serializers in Javascript are now synchronous, and should return a snapshot of the widget state. The default serializer makes a copy of JSONable objects. ([1270](https://github.com/jupyter-widgets/ipywidgets/pull/1270))
- Custom serializers can now return a structure that contains binary objects (`ArrayBuffer`, `DataView`, or a typed array such as `Int8Array`, `Float64Array`, etc.). In this case, the sync message will be a binary message, which is much more efficient for binary data than base64-encoding. The Image widget now uses this binary synchronization. ([1194](https://github.com/jupyter-widgets/ipywidgets/pull/1194), [#1643](https://github.com/jupyter-widgets/ipywidgets/pull/1643))
- A custom serializer is given the widget instance as its second argument, and a custom deserializer is given the widget manager as its second argument.
- The Javascript model `.id` attribute has been renamed to `.model_id` to avoid conflicting with the Backbone `.id` attribute. ([1410](https://github.com/jupyter-widgets/ipywidgets/pull/1410))
- Regarding widget managers and the syncing message protocol:
- The widget protocol was significantly overhauled. The new widget messaging protocol (version 2) is specified in the [version 2 protocol documentation](https://github.com/jupyter-widgets/ipywidgets/blob/main/jupyter-widgets-schema/messages.md).
- Widgets are now displayed with a `display_data` message instead of with a custom comm message. See the [ipywidgets](https://github.com/jupyter-widgets/ipywidgets/blob/20cd0f050090b1b19bb9657b8c3fa42ae384cfca/ipywidgets/widgets/widget.py#L656) implementation for an example. ([1274](https://github.com/jupyter-widgets/ipywidgets/pull/1274))
- Custom widget managers are now responsible completely for loading widget model and view classes. Widget managers should provide an output model and view class appropriate for their environment so that the `Output` widget works. ([1313](https://github.com/jupyter-widgets/ipywidgets/pull/1313))
- The widget manager `clear_state` method no longer has a `commlessOnly` argument. All models in the widget manager will be closed and cleared when `clear_state` is called. ([1354](https://github.com/jupyter-widgets/ipywidgets/pull/1354))