跨平台桌面程式開發框架，Qt 能幫你做到什麼

What's new in this version:

QTCORE:
- QLockFile: Fixed permissions on lock files on Unix to allow for adjustments via umask
- QMimeType: QMimeType::comment() now uses the default locale rather than system locale, so that applications can control which language is being used
- QUrl: QUrl::resolved() no longer treats a URL with a scheme as a relative URL if it matches this URL's scheme. For now it still treats "file:name.txt" as relative for compatibility, but be warned that in Qt 5.8 it will no longer consider those to be relative. Both isRelative() and RFC 3986 say that such URLs are not relative, so starting from Qt 5.8, resolved() will return them as is
- QXmlStreamReader: Fixed a bug in the XML parser that prevented to load XML that contained invalid characters for XML 1.0
- QXmlStreamWriter: Fixed a bug that prevented the generation of valid XML files when using encoding with 8 bit per character but not ASCII compatible. QXMLStreamWriter generated XML markup using always ASCII in this case

QTGUI:
- QGuiApplication: Fixed a bug that would cause QGuiApplication::sync() to be left undefined for Qt builds without session management support
- QIconLoaderEngine: Fixed theme lookup for scalable entries
- QTextDocument: Fixed a bug that would return a wrong position when searching backward from the end of the document
- Text: Fixed a performance regression in Freetype engine that was introduced in Qt 5.5
- Text: Fixed a crash that could happen if you were doing many different text layouts with different fonts and superscript or subscript alignment
- Text: Fixed bug where a QTextLayout with ShowLineAndParagraphSeparators would modify the layout's input string
- Text: Fixed performance regression when rapidly switching between a large set of fonts

QTNETWORK:
- QSslSocket: Fixed a bug in SecureTransport backend that would cause a memory usage growth in case 'readBufferMaxSize' is set
- QSslSocket: Fixed a bug in SecureTransport backend where transmit was using invalid SSL context and reporting (incorrectly) some irrelevant errors as a result

QTSQL:
- Fixed QSqlQuery::prepare value truncation error when using UNSIGNED values in a MySQL database

QTWIDGETS:
- QAbstractItemDelegate: Show localized detailed tooltips and "What's this?" texts
- QTreeView: Fixed a key navigation bug when the columns were reordered

CONFIGURE & BUILD SYSTEM:
- Fixed Fontconfig vs. system FreeType configuration
- Fixed detection of GLX with -qt-xcb
- [Windows] The configure.exe bootstrapping now prefers cl over clang-cl, to avoid header incompatibility problems
- Fixed missing plugins.qmltypes files in static builds
- Fixed dynamic library support detection for platforms without libdl
- Fixed running of configure tests outside qtbase when cross compiling on Windows (for example for Android)
- The flags supplied by the configure -D/-I/-L/-l options are now applied after Qt's own flags. This helps in some cases when the provided paths contain files which conflict with the Qt build
- Fixed linkage of QML plugins in static prefix builds
- [Unix] Fixed -no-pkg-config being ignored by some configure tests, which led to build failures later on
- Fixed configure tests outside qtbase when $MAKEFLAGS contains the -i flag
- [Android] Some unused plugins are not built anymore
- [MinGW] Added support for -separate-debug-info
- [Unix] Added configure -no-opengles3 option
- [Unix] Fixed MySQL detection/use on RHEL 6.6

QMAKE:
- Fixed nested custom functions inheriting their callers' arguments
- [MSVC] Started using separate PDB files for compiling and linking
- [Darwin] Fixed installation of debug symbols
- Various QMAKE_EXTRA_COMPILERS' .depends entries are now appended to rather than overwritten
- [MSys/Apple] Fixed detection of QMAKE_DEFAULT_{INC,LIB}DIRS
- Fixed access to freed memory in $$absolute_path()
- The obsolete -target xp is now properly rejected
- [nmake] _WINDLL is now automatically defined when building a DLL, consistently with Visual Studio
- Fixed build of projects with spaces in the source or build path against static builds of Qt
- [Xcode] Fixed support for Xcode 8
- [MinGW] Fixed -release -force-debug-info missing both optimization and debug info
- Fixed several cases where the error() function would not abort qmake
- Interrupting a command run via system() will now abort qmake as well
- The packagesExist() function will now warn when used when Qt was configured with -no-pkg-config
- [Android] The default compiler flags were adjusted to match newer NDK versions
- [Darwin] Fixed detection of QMAKE_DEFAULT_INCDIRS
- [Darwin][make] Added support for building Xcode asset catalogs