Qt 4.8.7 -

export QT_X11_NO_MITSHM=1 export XLIB_SKIP_ARGB_VISUALS=1 QString str = "Hello"; QByteArray utf8 = str.toUtf8(); // correct // avoid: str.toAscii() or str.latin1() Missing std::sqrt or C++11 features Qt 4.8.7 expects C++98. Use qSqrt() from <QtGlobal> or #include <math.h> . No automatic high-DPI Use QApplication::setFont(QFont("Arial", 16)) or set environment variable:

Add to your ~/.bashrc :

configure -platform win32-g++ -prefix C:\Qt\4.8.7 mingw32-make mingw32-make install main.cpp qt 4.8.7

qmake -project qmake make ./your_app

wget https://download.qt.io/archive/qt/4.8/4.8.7/qt-everywhere-opensource-src-4.8.7.tar.gz Alternate: https://download.qt.io/archive/qt/4.8/4.8.7/ Linux (Ubuntu 18.04/20.04 example) sudo apt-get install build-essential libgl1-mesa-dev libglu1-mesa-dev \ libx11-dev libxext-dev libxtst-dev libxrender-dev libxrandr-dev \ libxcursor-dev libxfixes-dev libxi-dev libxinerama-dev libfreetype6-dev \ libfontconfig1-dev libdbus-1-dev libssl-dev tar xzf qt-everywhere-opensource-src-4.8.7.tar.gz cd qt-everywhere-opensource-src-4.8.7 ./configure -prefix /opt/qt487 -opensource -confirm-license -nomake examples -nomake demos make -j$(nproc) sudo make install | Feature | Qt 4

TEMPLATE = app QT += core gui greaterThan(QT_MAJOR_VERSION, 4): QT += widgets SOURCES += main.cpp Note: QT += widgets is ignored in Qt 4 – keep it for minimal cross-compatibility. | Feature | Qt 4.8.7 | Qt 5/6 | |-----------------------|-------------------------------|-----------------------------| | Widgets module | QtGui | QtWidgets | | QString vs QByteArray | Less efficient Unicode | Better Unicode handling | | OpenGL | QGLWidget | QOpenGLWidget | | Threading | QThread (old style) | Better thread affinity | | Signals/slots | Macro-based (still works) | New syntax (function ptr) | | QML | Qt Quick 1.x (obsolete) | Qt Quick 2.x+ | | Platform plugins | X11, Windows, Cocoa (limited) | Wayland, Direct2D, etc. | 6. Debugging & Common Pitfalls Crash on modern Linux? Qt 4.8.7 uses X11 and older fontconfig. Set: Cocoa (limited) | Wayland