* Closes https://github.com/emilk/egui/issues/3816
Turn off with `style.interaction.multi_widget_text_select`.
There is an API for this in `LabelSelectionState`, but it's pretty
bare-bones.
This became really hairy implementation-wise, but it works decently
well.
# Limitations
* Drag-select to scroll doesn't work
* A selection disappears if you scroll past one of its end-points
* Only the text of labels and links are selectable
## TODO
* [x] An option to turn it off
* [x] An API for querying about the selected text, and to deselect it.
* [x] Scrolling past selection behaves weird
* [x] Shift-click to select a range
* squash before rebase
* Update AccessKit, introducing support for editable spinners on Windows and an important fix for navigation order on macOS
* Restore support for increment and decrement actions in DragValue
* Avoid VoiceOver race condition bug
* fix clippy lint
* Tell AccessKit that the default action for a text edit (equivalent to a click) is to set the focus. This matters to some platform adapters.
* Refactor InputState functions for AccessKit actions
* Support the AccessKit SetValue for DragValue; this is the only way for a Windows AT to programmatically adjust the value
* Same for Slider
* Properly associate the slider label with both the slider and the drag value
* Lazily activate egui's AccessKit support
* fix clippy lint
* Update AccessKit
* More documentation, particularly around lazy activation
* Tweak one of the doc comments
* See if I can get AccessKit exempted from the 'missing backticks' lint
* Make PlatformOutput::accesskit_update an Option
* Refactor lazy activation
* Refactor node mutation (again)
* Eliminate the need for an explicit is_accesskit_active method, at least for now
* Fix doc comment
* More refactoring of tree construction; don't depend on Arc::get_mut
* Override a clippy lint; I seem to have no other choice
* Final planned refactor: a more flexible approach to hierarchy
* Last AccessKit update for this PR; includes an important macOS DPI fix
* Move and document the optional accesskit dependency
* Fix comment typo
Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>
* reformat
* More elegant code for conditionally creating a node
Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>
* Set step to 1.0 for all integer sliders
* Add doc example for Response::labelled_by
* Clarify a TODO comment I left for myself
Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>
