Bugfixes:

• eventAllow and constraints not respected when dragging event between calendars
• viewSkeletonRender now in typedefs (#4589)
• invalid draggedEvent properties in eventAllow for external dnd (#4575)
• forceEventDuration not working with external dnd (#4597)
• rrule displaying time when allDay is true (#4576)
• rrule events not displaying at interval start (#4596)
• prev button not initially working when starting on 31st of a month (#4595)
• clicking X in popover generating a dayClick (#4584)
• locale file used as single script tag not affecting calendar locale (#4581)
• header "today" button not translated for pt and pt-br (#4591)
• fa locale typo (#4582)

Read about all the changes in v4:
https://fullcalendar.io/docs/upgrading-from-v3

Obscure breaking changes from v3->v4 not mentioned elsewhere:

• touchMouseIgnoreWait moved to (packageRoot).config.touchMouseIgnoreWait
• dataAttrPrefix moved to (packageRoot).config.dataAttrPrefix

Advancements since latest prerelease:

• New styling for buttons and icons in header. New styling for events.
• Bugfixes: #4539, #4503, #4534, #4505, #4477, #4467, #4454, #4458, #4483,
  #4517, #4506, #4435, #4498, #4497, #4446, #4432, #4530

NOTE: version "4.0.0" was skipped because of an NPM publishing error

BIG changes since last alpha release:
(see https://fullcalendar.io/docs/v4/release-notes for more info)

• all functionality is broken up into plugins
• changed the names of many views (ex: agendaWeek -> timeGridWeek)
• changed the names of the npm packages (ex: @fullcalendar/core)
• technique for initializing a calendar (and using plugins) has changed
• SuperAgent is no longer needed
• Bootstrap 3 theme support dropped
• jQuery UI theme support dropped
• Bower support dropped
• Composer support temporarily dropped
• a new npm-run based dev workflow
• bundled via Rollup (instead of Webpack)

Smaller changes since last alpha release:

• no need to specify timeZoneImpl setting. simply use luxon or moment-timezone plugin instead
• agendaEventMinHeight renamed to timeGridEventMinHeight
• for registering a custom view use createPlugin instead of defineView
• groupByDatesAndResources and groupByResources removed. Use datesAboveResources instead
• removed the deprecated theme settings. use themeSystem instead
• for Boostrap 4 theme support, specify themeSystem: 'boostrap' instead of ('bootstrap4')

Really obscure changes:

• MAX_TIMELINE_SLOTS moved to (packageRoot).config.MAX_TIMELINE_SLOTS
• touchMouseIgnoreWait moved to (packageRoot).config.touchMouseIgnoreWait
• dataAttrPrefix moved to (packageRoot).config.dataAttrPrefix

API changes:

• in eventDrop callback, the prevEvent property has been renamed to oldEvent

bugfixes that preexisted v4

• forceEventDuration takes wrong duration when switching between all day and timed event (#4097)
• first day in View, event spans from previous day ignoring nextDayThreshold (#3943)
• eventResize helper element should go through eventDestroy (#3543)
• set touchstart listeners as passive (#4149)

bugfixes for regressions: #4363, #4422, #4331, #4342, #4416, #4333, #4350, #4348, #4149, #4444

also, all bugfixes from v3.10.0 have been merged

POTENTIALLY BREAKING CHANGE:
The jquery and moment packages have been moved to peerDependencies. If you are using
NPM to install fullcalendar, you'll need to explicitly add jquery and moment as
dependencies of your project. NPM will not install them automatically. (#4136, #4233)

New Features:

• events from a Google Calendar event source will receive extended props (#4123)
• export more classes and util functions (#4124)
• new locales: zh-hk (#4266), be (#4274)

Bugfixes:

• not accepting dayClicks/selects because of overflow-x:hidden on html/body (#3615)
• event end time not displayed when duration is one slot, in agenda view (#3049)
• switching views before event fetch resolves, JS error (#3689)
• single-day allDay event not showing when time is specified (#3854)
• prev button doesn't work when previous days are hidden by hiddenDays and dayCount
  is greater than dateIncrement (#4202)
• calendar locale not used in all moments objects (#4174)
• background event background color does not completely fill cells in Chrome (#4145)
• provide a delta for eventResize when resizing from start (#4135)
• IE11 memory leak from not removing handler correctly (#4311)
• make touchstart handlers passive (#4087)
• fixed typescript definition for: eventAllow (#4243), selectAllow (#4319)
• fixed locales: de (#4197, #4371), hu (#4203), tr (#4312), ja (#4329)

Changes since last alpha release:

• Calendar::getView method removed. Use Calendar::view property instead
• the event JSON feed property extraData has been renamed extraParams
• the external Draggable property time has been renamed startTime
• the constraint setting can accept an array of objects
• MonthView class is no longer exposed. Has been rolled into BasicView,
  which is exposed instead.

Regressions from v3: #4421, #4420

More info:
https://fullcalendar.io/blog/2018/12/alpha-release-scheduler-support
https://fullcalendar.io/docs/v4/release-notes

Please read https://fullcalendar.io/docs/v4/release-notes

Please read https://fullcalendar.io/blog/2018/04/alpha-release-jquery-removal

• Bootstrap 4 support (#4032, #4065, thx @GeekJosh)
• add OptionsInput to the fullcalendar.d.ts exports (#4040, #4006)
• columnHeaderFormat/columnHeaderHtml/columnHeaderText in .d.ts file (#4061, #4085)
• list-view auto-height not working (#3346, #4071, thx @WhatTheBuild)
• bump momentjs minimum version to 2.20.1, for locale fixes (#4014)
• swedish week header translation fix (#4082)
• dutch year translation (#4069)

Bugfixes:

• Fix TypeScript definitions file with strictNullChecks (#4035)