PyQt

If you omit the dir argument (or pass in an empty string), the dialog should remember the last directory:

    filename = QtGui.QFileDialog.getOpenFileName(                   parent, 'Open File', '', 'Images (*.png *.xpm *.jpg)')

The tr function is used for translating user-visible strings. You can omit it if you won't ever be providing translations for your application.

EDIT:

It seems that the start directory may not be automatically remembered on all platforms/desktops, depending on whether you use the native dialog or not. If Qt's built-in dialog is used, the start directory should always be automatically remebered on all platforms (even between invokations of the application). To try the non-native dialog, do:

    filename = QtGui.QFileDialog.getOpenFileName(                   parent, 'Open File', '', 'Images (*.png *.xpm *.jpg)',                   None, QtGui.QFileDialog.DontUseNativeDialog)

Alternatively, you can use the QFileDialog constructor, which will always create a non-native dialog:

    dialog = QtGui.QFileDialog(parent)    dialog.setWindowTitle('Open File')    dialog.setNameFilter('Images (*.png *.xpm *.jpg)')    dialog.setFileMode(QtGui.QFileDialog.ExistingFile)    if dialog.exec_() == QtGui.QDialog.Accepted:        filename = dialog.selectedFiles()[0]