1 Some of the changes listed in this file include issue tracking numbers
2 corresponding to tasks in the Qt Bug Tracker:
4 http://bugreports.qt-project.org/
6 Each of these identifiers can be entered in the bug tracker to obtain more
7 information about a particular change.
10 ****************************************************************************
11 * Source incompatible changes *
12 ****************************************************************************
15 - QSslCertificate::subjectInfo() and QSslCertificate::issuerInfo() now
16 return a QStringList instead of a QString
18 - QSslCertificate::isValid() has been deprecated. Originally it only checked
19 the certificate dates, but later checking for blacklisting was added. Now
20 there's a more specific QSslCertificate::isBlacklisted() method.
22 - Unite clipping support has been removed from QPainter. The alternative is
23 to unite QRegion's and using the result on QPainter.
25 - QLibrary::resolve() now returns a function pointer instead of a void
28 - QSslCertificate::alternateSubjectNames() is deprecated (but can be enabled
29 via QT_DISABLE_DEPRECATED_BEFORE), use
30 QSslCertificate::subjectAlternativeNames() instead.
32 - QLibraryInfo::buildKey() has been removed. Likewise, the QT_BUILD_KEY
33 preprocessor #define has also been removed. The build-key is obsolete
34 and is no longer necessary.
36 - QCoreApplication::translate() will no longer return the source text when
37 the translation is empty. Use lrelease -removeidentical for optimization.
39 - QString and QByteArray constructors that take a size argument will now treat
40 negative sizes to indicate nul-terminated strings (a nul-terminated array of
41 QChar, in the case of QString). In Qt 4, negative sizes were ignored and
42 result in empty QString and QByteArray, respectively. The size argument to
43 those constructors now has a default value of -1, thus replacing the separate
44 constructors that did the same.
46 - Qt::escape() is deprecated (but can be enabled via
47 QT_DISABLE_DEPRECATED_BEFORE), use QString::toHtmlEscaped() instead.
49 - QBool is gone. QString::contains, QByteArray::contains, and QList::contains
50 used to return an internal QBool class so that the Qt3 code
51 "if (a.contains() == 2)" wouldn't compile anymore. Such code cannot exist
52 in Qt4, so these methods return a bool now. If your code used the undocumented
53 QBool, simply replace it with bool.
55 - qIsDetached<> has been removed without replacement.
58 * QMetaType::construct() has been renamed to QMetaType::create().
59 * QMetaType::unregisterType() has been removed.
62 * QMetaMethod::signature() has been renamed to QMetaMethod::methodSignature(),
63 and the return type has been changed to QByteArray. This was done to be able
64 to generate the signature string on demand, rather than always storing it in
66 * QMetaMethod::typeName() no longer returns an empty string when the return
67 type is void; it returns "void". The recommended way of checking whether a
68 method returns void is to compare the return value of QMetaMethod::returnType()
72 * Inconsistent constructor taking Qt::GlobalColor and producing QVariant(QColor)
73 instance was removed. Code constructing such variants can be migrated by
74 explicitly calling QColor constructor. For example from "QVariant(Qt::red)"
75 to "QVariant(QColor(Qt::red))"
78 * The plain-text, xml and lightxml test output formats have been changed to
79 show a test result for every row of test data in data-driven tests. In
80 Qt4, only fails and skips were shown for individual data rows and passes
81 were not shown for individual data rows, preventing accurate calculation
82 of test run rates and pass rates.
83 * The QTRY_VERIFY and QTRY_COMPARE macros have been moved into QTestLib.
84 These macros formerly lived in tests/shared/util.h but are now provided
85 by including the <QtTest/QtTest> header. In addition,
86 QTRY_VERIFY_WITH_TIMEOUT and QTRY_COMPARE_WITH_TIMEOUT are provided,
87 allowing for specifying custom timeout values.
88 * The QTEST_NOOP_MAIN macro has been removed from the API. If a test is
89 known at compile-time to be inapplicable for a particular build it should
90 be omitted via .pro file logic, or the test should call QSKIP in the
91 initTestCase() method to skip the entire test and report a meaningful
92 explanation in the test log.
93 * The DEPENDS_ON macro has been removed from the API. This macro did nothing
94 and misled some users to believe that they could make test functions depend
95 on each other or impose an execution order on test functions.
96 * The QTest::qt_snprintf function has been removed from the API. This was an
97 internal testlib function that was exposed in the public API due to its use
98 in a public macro. Any calls to this function should be replaced by a call
99 to qsnprintf(), which comes from the <QtCore/QByteArray> header.
100 * The QTest::pixmapsAreEqual() function has been removed from the API.
101 Comparison of QPixmap objects should be done using QCOMPARE, which provides
102 more informative output in the event of a failure.
103 * The QSKIP macro no longer has the "mode" parameter, which caused problems
104 for calculating test metrics, as the SkipAll mode hid information about
105 what test data was skipped. Calling QSKIP in a test function now behaves
106 like SkipSingle -- skipping a non-data-driven test function or skipping
107 only the current data row of a data-driven test function. Every skipped
108 data row is now reported in the test log.
110 - The QSsl::TlsV1 enum value was renamed to QSsl::TlsV1_0 .
113 * Internal QAccessible::State enum value HasInvokeExtension removed
114 - QAccessibleInterface:
115 * The "child" integer parameters have been removed. This moves the api
116 to be closer to IAccessible2.
117 This means several functions lose their integer parameter:
118 text(Text t, int child) -> text(Text t), rect(int child) -> rect()
119 setText(Text t, int child, const QString &text) -> setText(Text t, const QString &text)
120 role(int child) -> role(), state(int child) -> state()
121 * parent() and child() was added in order to do hierarchical navigation.
122 * relations() was added as a replacement to relationTo()
123 * As a consequence of the above two points, navigate() was removed.
124 * Accessible-Action related functions have been removed. QAccessibleInterface
125 subclasses are expected to implement the QAccessibleActionInterface instead.
126 These functions have been removed:
127 QAccessibleInterface::userActionCount, QAccessibleInterface::actionText,
128 QAccessibleInterface::doAction
129 - QAccessibleEvent also loses the child parameter.
130 QAccessibleEvent(Type type, int child) -> QAccessibleEvent(Type type)
131 QAccessibleEvent::child() removed.
132 - QAccessibleActionInterface:
133 * Refactored to be based on action names. All functions have been changed from using
134 int parameters to strings.
136 - QSound has been moved from QtGui to QtMultimedia
138 - QTabletEvent::QTabletEvent does not take a hiResGlobalPos argument anymore,
139 as all coordinates are floating point based now.
143 * The DeviceType enum and deviceType() have been deprecated due to
144 the introduction of QTouchDevice.
146 * The signature of the constructor has changed. It now takes a
147 QTouchDevice pointer instead of just a DeviceType value.
149 * TouchPointState no longer includes TouchPointStateMask and
150 TouchPointPrimary. QTouchEvent::TouchPoint::isPrimary() has
153 * QWidget *widget() has been removed and is replaced by QObject
154 *target() in order to avoid QWidget dependencies.
156 * QEvent::TouchCancel has been introduced. On systems where it makes
157 sense this event type can be used to differentiate between a
158 regular TouchEnd and abrupt touch sequence cancellations caused by
159 the compositor, for example when a system gesture gets recognized.
163 * Q_DECLARE_METATYPE(Foo*) now requires that Foo is fully defined. In
164 cases where a forward declared type should be used as a metatype,
165 Q_DECLARE_OPAQUE_POINTER(Foo*) can be used to allow that.
169 * The signature of the createEditor and valuePropertyName methods
170 have been changed to take arguments of type int instead of QVariant::Type.
172 - QWindowSystemInterface:
174 * The signature of all handleTouchEvent() variants have changed,
175 taking a QTouchDevice* instead of just a DeviceType value.
176 Platform or generic plug-ins have to create and register at least
177 one QTouchDevice before sending the first touch event.
179 * The event type parameter is removed from handleTouchEvent().
181 - The previously exported function qt_translateRawTouchEvent() has been removed.
182 Use QWindowSystemInterface::handleTouchEvent() instead.
184 - QAbstractEventDispatcher
186 * The signature for the pure-virtual registerTimer() has changed. Subclasses
187 of QAbstractEventDispatcher will need to be updated to reimplement the new
188 pure-virtual 'virtual void registerTimer(int timerId, int interval,
189 Qt::TimerType timerType, QObject *object) = 0;'
191 * QAbstractEventDispatcher::TimerInfo is no longer a QPair<int, int>. It is
192 now a struct with 3 members: struct TimerInfo { int timerId; int interval;
193 Qt::TimerType timerType; }; Reimplementations of
194 QAbstractEventDispatcher::registeredTimers() will need to be updated to pass
195 3 arguments to the TimerInfo constructor (instead of 2).
199 * Removed implicit conversion operator QUuid::operator QString(), instead
200 QUuid::toString() function should be used.
202 - The QHttp, QHttpHeader, QHttpResponseHeader and QHttpRequestHeader classes have
203 been removed, QNetworkAccessManager should be used instead.
205 - The QFtp class is no longer exported, QNetworkAccessManager should be used
210 * On Windows, QProcess::ForwardedChannels will not forward the output of GUI
211 applications anymore, if they do not create a console.
213 - QAbstractSocket's connectToHost() and disconnectFromHost() are now virtual and
214 connectToHostImplementation() and disconnectFromHostImplementation() don't exist.
216 - QTcpServer::incomingConnection() now takes a qintptr instead of an int.
218 - QNetworkConfiguration::bearerName() removed, and bearerTypeName() should be used.
220 - QDir::convertSeparators() (deprecated since Qt 4.2) has been removed. Use
221 QDir::toNativeSeparators() instead.
223 - QIconEngineV2 was merged into QIconEngine
224 You might need to adjust your code if it used a QIconEngine.
227 * Projects which explicitly set an empty TARGET are considered broken now.
228 * The makespec and .qmake.cache do not see build pass specific variables any more.
229 * load()/include() with a target namespace and infile()/$$fromfile() now start with
230 an entirely pristine context.
231 * Configure's -sysroot and -hostprefix are now handled slightly differently.
232 The QT_INSTALL_... properties are now automatically prefixed with the sysroot;
233 the raw values are available as QT_INSTALL_.../raw and the sysroot as QT_SYSROOT.
234 The new QT_HOST_... properties can be used to refer to the Qt host tools.
235 * Several functions and built-in variables were modified to return normalized paths.
237 - QTextCodecPlugin has been removed since it is no longer used. All text codecs
238 are now built into QtCore.
240 - QDir::NoDotAndDotDot is QDir::NoDot|QDir::NoDotDot therefore there is no need
241 to use or check both.
243 - QFSFileEngine, QAbstractFileEngine, QAbstractFileEngineIterator and
244 QAbstractFileEngineHandler were removed from public API and are no longer
245 exported. They may temporarily live as private implementation details, but
246 they may be altogether dropped or otherwise changed at will in the future.
249 * toShort(), toUShort(), toInt(), toUInt(), toLongLong() and toULongLong() no
250 longer take a parameter for base, they will only perform localised base 10
251 conversions. For converting other bases use the QString methods instead.
253 - QSystemLocale has been removed from the public API.
255 - QSqlQueryModel::indexInQuery() is now virtual. See note below under QtSql.
257 - QSqlDriver::subscribeToNotification, unsubscribeFromNotification,
258 subscribedToNotifications, isIdentifierEscaped, and stripDelimiters
259 are now virtual. See note below under QtSql.
261 - qMacVersion() has been removed. Use QSysInfo::macVersion() or
262 QSysInfo::MacintoshVersion instead.
264 - QColorDialog::customColor() now returns a QColor value instead of QRgb.
265 QColorDialog::setCustomColor() and QColorDialog::setStandardColor() now
266 take a QColor value for their second parameter instead of QRgb.
268 ****************************************************************************
270 ****************************************************************************
275 - The directory structure of the qtbase unit-tests has been reworked to
276 more closely match the directory structure of the code under test.
277 Integration tests have been moved to tests/auto/integrationtests.
279 Third party components
280 ----------------------
285 ****************************************************************************
287 ****************************************************************************
291 * drop a bogus QChar::NoCategory enum value; the proper QChar::Other_NotAssigned
292 value is returned for an unassigned codepoints now.
294 * layoutAboutToBeChanged is no longer emitted by QAbstractItemModel::beginMoveRows.
295 layoutChanged is no longer emitted by QAbstractItemModel::endMoveRows. Proxy models
296 should now also connect to (and disconnect from) the rowsAboutToBeMoved and
299 * The default value of the property QSortFilterProxyModel::dynamicSortFilter was
300 changed from false to true.
302 * The signature of the virtual QAbstractItemView::dataChanged method has changed to
303 include the roles which have changed. The signature is consistent with the dataChanged
306 * QFileSystemWatcher is now able to return failure in case of errors whilst
307 altering the watchlist in both the singular and QStringList overloads of
308 addPath and removePath.
310 * QString::mid, QString::midRef and QByteArray::mid, if the position passed
311 is equal to the length (that is, right after the last character/byte),
312 now return an empty QString, QStringRef or QByteArray respectively.
313 in Qt 4 they returned a null QString or a null QStringRef.
315 * QString methods toLongLong(), toULongLong(), toLong(), toULong(), toInt(),
316 toUInt(), toShort(), toUShort(), toDouble(), and toFloat() no longer use the
317 default or system locale, they will always use the C locale. This is to
318 guarantee consistent default conversion of strings. For locale-aware conversions
319 use the equivalent QLocale methods.
321 * QDate, QTime, and QDateTime have undergone important behavioural changes:
322 * QDate only implements the Gregorian calendar, the switch to the Julian
323 calendar before 1582 has been removed. This means all QDate methods will
324 return different results for dates prior to 15 October 1582, and there is
325 no longer a gap between 4 October 1582 and 15 October 1582.
326 * QDate::setYMD() is deprecated, use QDate::setDate() instead
327 * Most methods now apply strict validity checks and will return appropriate
328 and consistent values when invalid. For example, QDate::year() will return
329 0 and QDate::shortMonthName() will return QString().
330 * Adding days to a null QDate or seconds to a null QTime will no longer return
332 * QDate stores the Julian Day as a qint64 extending date support across a
333 more interesting range, see the class documentation for details.
334 * Conversion to YMD form dates is only accurate between to 4800 BCE to
336 * The QDate::addDays() and QDateTime::addDays() methods now take a qint64
337 * The QDate::daysTo() and QDateTime::daysTo() methods now return a qint64
339 * QTextCodec::codecForCStrings() and QTextCodec::setCodecForCStrings() have both
340 been removed. This was removed due to issues with breaking other code from
341 libraries, creating uncertainty/bugs in using QString easily, and (to a lesser
342 extent) performance issues.
344 * QTextCodec::codecForTr() and QTextCodec::setCodecForTr() have been removed,
345 QCoreApplication::Encoding value CodecForTr is now obsolete, use
346 DefaultCodec instead. For reasoning, see the codecForCStrings() removal above.
348 * QIntValidator and QDoubleValidator no longer fall back to using the C locale if
349 the requested locale fails to validate the input.
351 * A new set of classes for doing pattern matching with Perl-compatible regular
352 expressions has been added: QRegularExpression, QRegularExpressionMatch and
353 QRegularExpressionMatchIterator. They aim to replace QRegExp with a more
354 powerful and flexible regular expression engine.
356 * Certain methods in QRegExp that modified the object's internals are no longer marked
357 const. They were accidentally marked const in Qt 4 but the problem could not be
358 fixed. The following are suggestions to adapt code to this change:
359 - make sure the QRegExp object is not const in the given context
360 - create a copy of the QRegExp object before using it
361 - invert the operation and use QString. E.g., rx.indexIn(string) becomes string.indexOf(rx)
363 * QEvent::AccessibilityPrepare, AccessibilityHelp and AccessibilityDescription removed:
364 * The enum values simply didn't make sense in the first place and should simply be dropped.
366 * [QTBUG-23529] QHash is now more resilient to a family of denial of service
367 attacks exploiting algorithmic complexity, by supporting two-arguments overloads
368 of the qHash() hashing function.
372 * Accessibility has been refactored. The hierachy of accessible objects is implemented via
373 proper parent/child functions instead of using navigate which has been deprecated for this purpose.
374 Table and cell interfaces have been added to qaccessible2.h
376 * Touch events and points have been extended to hold additional
377 information like capability flags, point-specific flags, velocity,
380 * A new set of enabler classes have been added, most importantly QWindow, QScreen,
381 QSurfaceFormat, and QOpenGLContext.
383 * Most of the useful QtOpenGL classes have been polished and moved into
384 QtGui. See QOpenGLFramebufferObject, QOpenGLShaderProgram,
385 QOpenGLFunctions, etc.
387 * QOpenGLPaintDevice has been added to be able to use QPainter to render into
388 the currently bound context.
392 * QInputContext removed as well as related getters and setters on QWidget and QApplication.
393 Input contexts are now platform specific.
395 * QInputDialog::getInteger() has been obsoleted. Use QInputDialog::getInt() instead.
397 * In Qt 4, many QStyleOption subclasses were introduced in order to keep
398 binary compatibility -- QStyleOption was designed to be extended this way,
399 in fact it embeds a version number. In Qt 5 the various QStyleOption*V{2,3,4}
400 classes have been removed, and their members merged into the respective
401 base classes. Those classes were left as typedefs to keep existing code
402 working. Still, some minor adjustements could be necessary, especially in code
403 that uses QStyleOption directly and does not initialize all the members using
404 the proper Qt API: due to the version bump, QStyle will try to use the additional
405 QStyleOption members, which are left default-initialized.
407 * QHeaderView - The following functions have been obsoleted.
409 * void setMovable(bool movable) - use void setSectionsMovable(bool movable) instead.
411 * bool isMovable() const - use bool sectionsMovable() const instead.
413 * void setClickable(bool clickable) - use void setSectionsClickable(bool clickable) instead.
415 * bool isClickable() const - use bool sectionsClickable() instead.
417 * void setResizeMode(int logicalindex, ResizeMode mode) -
418 use setSectionResizeMode(logicalindex, mode) instead.
420 * ResizeMode resizeMode(int logicalindex) const -
421 use sectionResizeMode(int logicalindex) instead.
423 * QDateEdit and QTimeEdit have re-gained a USER property. These were originally removed
424 before Qt 4.7.0, and are re-added for 5.0. This means that the userProperty for
425 those classes are now QDate and QTime respectively, not QDateTime as they have been
426 for the 4.7 and 4.8 releases.
430 * QHostAddress::isLoopback() API added. Returns true if the address is
431 one of the IP loopback addresses.
433 * QSslCertificate::serialNumber() now always returns the serial number in
436 * The openssl network backend now reads the ssl configuration file allowing
437 the use of openssl engines.
441 * QtDBus now generates property annotations for the Qt type names
442 in the org.qtproject.QtDBus namespace. When parsing such annotations
443 both the old and new namespaces are accepted.
445 * QtDBus error codes have been updated to be on the org.qtproject.QtDBus.Error
451 * Most of the classes in this module (with the notable exception of QGLWidget)
452 now have equivalents in QtGui, along with the naming change QGL -> QOpenGL.
453 The classes in QtOpenGL that have equivalents in QtGui can now be considered
462 * [QTBUG-20615] Autotests can now log test output to multiple destinations
463 and log formats simultaneously.
467 QSqlQueryModel/QSqlTableModel/QSqlRelationalTableModel
469 * The dataChanged() signal is now emitted for changes made to an inserted
470 record that has not yet been committed. Previously, dataChanged() was
471 suppressed in this case for OnRowChange and OnFieldChange. This was probably
472 an attempt to avoid trouble if setData() was called while handling
473 primeInsert(). By emitting dataChanged(), we ensure that all views are aware
476 * While handling primeInsert() signal, the record must be manipulated using
477 the provided reference. Do not attempt to manipulate the records using the
478 model methods setData() or setRecord().
480 * removeRows() no longer emits extra beforeDelete signal for out of range row.
482 * removeRows() now requires the whole range of targetted rows to be valid
483 before doing anything. Previously, it would remove what it could and
484 ignore the rest of the range.
486 * removeRows(), for OnFieldChange and OnRowChange, allows only 1 row to be
487 removed and only if there are no other changed rows.
489 * setRecord() and insertRecord()
490 -Only use fields where generated flag is set to true. This is
491 is consistent with the meaning of the flag.
492 -Require all fields to map correctly. Previously fields that didn't
493 map were simply ignored.
494 -For OnManualSubmit, insertRecord() no longer leaves behind an empty
495 row if setRecord() fails.
496 -setRecord() now automatically submits for OnRowChange.
498 * QSqlQueryModel::indexInQuery() is now virtual. See
499 QSqlTableModel::indexInQuery() as example of how to implement in a
502 * QSqlQueryMode::setQuery() emits fewer signals. The modelAboutToBeReset()
503 and modelReset() signals suffice to inform views that they must reinterrogate
506 * QSqlTableModel::selectRow(): This is a new method that refreshes a single
507 row in the model from the database.
509 * QSqlTableModel edit strategies OnFieldChange/OnRowChange QTBUG-2875
510 Previously, after changes were submitted in these edit strategies, select()
511 was called which removed and inserted all rows. This ruined navigation
512 in QTableView. Now, with these edit strategies, there is no implicit select()
513 done after committing. This includes deleted rows which remain in
514 the model as blank rows until the application calls select(). Instead,
515 selectRow() is called to refresh only the affected row.
517 * QSqlTableModel::isDirty(): New overloaded method to check whether model
518 has any changes to submit. QTBUG-3108
520 * QSqlTableModel::setData() and setRecord() no longer revert pending changes
521 that fail upon resubmitting for edit strategies OnFieldChange and OnRowChange.
522 Instead, pending (failed) changes cause new changes inappropriate to the
523 edit strategy to be refused. The application should resolve or revert pending
524 changes. insertRows() and insertRecord() also respect the edit strategy.
526 * QSqlTableModel::setData() and setRecord() in OnRowChange no longer have the
527 side effect of submitting the cached row when invoked on a different row.
529 * QSqlDriver::subscribeToNotification, unsubscribeFromNotification,
530 subscribedToNotifications, isIdentifierEscaped, and stripDelimiters
531 are now virtual. Their xxxImplemenation counterparts have been removed
532 now that QSqlDriver subclasses can reimplement these directly.
534 ****************************************************************************
536 ****************************************************************************
540 * QVariant::Bool type now mapped to integers 0/1 in SQL instead of strings
541 'true' and 'false'. Sqlite does not have a boolean column type and it is
542 customary to use integer. QTBUG-23895
544 ****************************************************************************
545 * Platform Specific Changes *
546 ****************************************************************************
554 * Accessibility framework uses IAccessible2
561 Qt for Embedded Linux
562 ---------------------
569 ****************************************************************************
570 * Compiler Specific Changes *
571 ****************************************************************************
574 ****************************************************************************
576 ****************************************************************************
580 * Remove qttest_p4.prf file. From now on we should explicitly enable the
581 things from it which we want. Autotest .pro files should stop using
582 'load(qttest_p4)' and start using 'CONFIG+=testcase' instead.
587 * [QTBUG-8926] [QTBUG-20440] Properties of type QStringList now have
588 translation attributes which apply to all items.
589 They are by default translatable.
598 * [QTBUG-20785] The moc now has a -b<file> option to #include an additional
599 file at the beginning of the generated file.
610 * QMAKE_MOC_OPTIONS variable is now available for passing additional parameters
620 ****************************************************************************
622 ****************************************************************************
623 - The text codecs that were previously plugins are now built into QtCore.
625 ****************************************************************************
626 * Important Behavior Changes *
627 ****************************************************************************
631 * The implementation of QPointer has been changed to use QWeakPointer. The
632 old guard mechanism has been removed. This causes a slight change
633 in behavior when using QPointer:
635 * When using QPointer on a QWidget (or a subclass of QWidget), previously
636 the QPointer would be cleared by the QWidget destructor. Now, the QPointer
637 is cleared by the QObject destructor (since this is when QWeakPointers are
638 cleared). Any QPointers tracking a widget will NOT be cleared before the
639 QWidget destructor destroys the children for the widget being tracked.
643 * QUrl has been changed to operate only on percent-encoded
644 forms. Fully-decoded forms, where the percent character stands for itself,
645 are no longer possible. For that reason, the getters and setters with
646 "encoded" in the name are deprecated, except for QUrl::toEncoded() and
649 QUrl now operates in a mode where it decodes as much as it can of the
650 percent-encoding sequences. In addition, the setter methods possess a mode
651 in which a '%' character not part of a percent-encoding sequence will cause
652 the parser to correct the input. Therefore, most software will not require
653 changes to adapt, since the getter methods will continue returning the
654 components in their most-decoded form as they did before and the setter
655 methods will accept input as they did before..
657 The most notable difference is when dealing with
658 QUrl::toString(). Previously, this function would return percent characters
659 in the URL by themselves. Now, it will return "%25", like
664 * Definition of QVariant::UserType changed. Currently it is the same as
665 QMetaType::User, which means that it points to the first registered custom
666 type, instead of a nonexistent type.
670 * Interpretation of QMetaType::Void was changed. Before, in some cases
671 it was returned as an invalid type id, but sometimes it was used as a valid
672 type (C++ "void"). In Qt5, new QMetaType::UnknownType was introduced to
673 distinguish between these two. QMetaType::UnknownType is an invalid type id
674 signaling that a type is unknown to QMetaType, and QMetaType::Void
675 is a valid type id of C++ void type. The difference will be visible for
676 example in call to QMetaType::typeName(), this function will return null for
677 QMetaType::UnknownType and a pointer to "void" string for
679 Please, notice that QMetaType::UnknownType has value 0, which previously was
680 reserved for QMetaType::Void.
685 * The static function QMessageBox::question has changed the default argument
686 for buttons. Before the default was to have an Ok button. That is changed
687 to having a yes and a no button.