$ make
g++ -c -pipe -Wall -W -O2 -D_REENTRANT -DQT_NO_DEBUG -DQT_THREAD_SUPPORT  -I/usr/share/qt3/mkspecs/default -I. -I. -I/usr/include/qt3 -o main.o main.cpp
g++  -o qt main.o    -L/usr/X11R6/lib -lXext -lX11 -lm -lpthread
main.o: In function `main':
main.cpp:(.text+0x1f): undefined reference to `QApplication::QApplication(int&, char**)'
main.cpp:(.text+0x2f): undefined reference to `QString::QString(char const*)'
main.cpp:(.text+0x43): undefined reference to `QPushButton::QPushButton(QString const&, QWidget*, char const*)'
main.cpp:(.text+0x58): undefined reference to `QString::shared_null'
main.cpp:(.text+0x63): undefined reference to `QStringData::deleteSelf()'
main.cpp:(.text+0x71): undefined reference to `QPushButton::resize(int, int)'
main.cpp:(.text+0x7a): undefined reference to `QApplication::setMainWidget(QWidget*)'
main.cpp:(.text+0x82): undefined reference to `QWidget::show()'
main.cpp:(.text+0x8a): undefined reference to `QApplication::exec()'
main.cpp:(.text+0x94): undefined reference to `QPushButton::~QPushButton()'
main.cpp:(.text+0x9c): undefined reference to `QApplication::~QApplication()'
main.cpp:(.text+0xba): undefined reference to `QString::shared_null'
main.cpp:(.text+0xc5): undefined reference to `QStringData::deleteSelf()'
main.cpp:(.text+0xd1): undefined reference to `QApplication::~QApplication()'
main.cpp:(.text+0xe9): undefined reference to `QPushButton::~QPushButton()'
main.o:(.gnu.linkonce.r._ZTI6QGList[typeinfo for QGList]+0x8): undefined reference to `typeinfo for QPtrCollection'
main.o:(.gnu.linkonce.r._ZTV6QGList[vtable for QGList]+0xc): undefined reference to `QGList::clear()'
main.o:(.gnu.linkonce.r._ZTV6QGList[vtable for QGList]+0x10): undefined reference to `QGList::~QGList()'
main.o:(.gnu.linkonce.r._ZTV6QGList[vtable for QGList]+0x14): undefined reference to `QGList::~QGList()'
main.o:(.gnu.linkonce.r._ZTV6QGList[vtable for QGList]+0x18): undefined reference to `QPtrCollection::newItem(void*)'
main.o:(.gnu.linkonce.r._ZTV6QGList[vtable for QGList]+0x20): undefined reference to `QGList::compareItems(void*, void*)'
main.o:(.gnu.linkonce.r._ZTV6QGList[vtable for QGList]+0x24): undefined reference to `QGList::read(QDataStream&, void*&)'
main.o:(.gnu.linkonce.r._ZTV6QGList[vtable for QGList]+0x28): undefined reference to `QGList::write(QDataStream&, void*) const'
collect2: ld returned 1 exit status
make: *** [qt] Error 1