The qt driver uses the the Qt library (either Qt4 or Qt5) to implement the qtwidget interactive device. Text and graphics are antialised, font selection is done automatically for any given unicode glyph requested using the recommended fontconfig approach, and complex text layout is used to render text. As a result the qtwidget device is considered to be one of our three best (the other two are described in the section called “The cairo driver”) interactive devices in terms of graphical and text rendering quality. However, this device's raw interactive capabilities are still immature compared to those described in the section called “The xwin driver”. For example, the interactive parts of standard example 20 do not yet work correctly with the qtwidget device. Furthermore, the GUI capability of this device needs enhancing, e.g., to reorient or zoom plots or to provide a cmap0 and cmap1 palette editor.