Qt is a GUI library, and PyQt is a Python library extension that makes Qt available to Python scripts.  There are Open Source versions available of all the component parts you'll need for Linux (indeed, you'll possibly find the whole thing is there as part of your Linux distribution) and it's also available under license for use on Windows.

Newcomers to GUI programming are often baffled by the great thick manuals, but basically it comes down to widgets, layouts and events (characterised as slots and signals in Qt) that you need to understand early on.

Here's an example program in Python, using PyQt and Qt, which produced a window with a number in it, and "lower" and "higher" buttons.  Press "lower" and the number goes down by 1, press "higher" and the number goes up by 1 ....

Code:

import sys from qt import * class MainWindow(QMainWindow):    val = 17    def __init__(self, *args):        apply(QMainWindow.__init__, (self, ) + args)        self.vlayout = QHBoxLayout(self, 10, 5)        self.labelValue = QLabel(str(MainWindow.val), self)        self.down = QPushButton("Lower", self)        self.up = QPushButton("Higher", self)        self.vlayout.addWidget(self.down)        self.vlayout.addWidget(self.labelValue)        self.vlayout.addWidget(self.up)        self.connect(self.down, SIGNAL("clicked()"), self.reduce)        self.connect(self.up, SIGNAL("clicked()"), self.increase)    def reduce(self):        MainWindow.val -= 1        self.setval()    def increase(self):        MainWindow.val += 1        self.setval()    def setval(self):        self.labelValue.setText(str(MainWindow.val)) def main(args):    app=QApplication(args)    win=MainWindow()    win.show()    app.connect(app, SIGNAL("lastWindowClosed()")                , app                , SLOT("quit()")                )    app.exec_loop() if __name__=="__main__":        main(sys.argv)

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