The preference dialog is used to customize the application. It has six differents tabs. If you confirm your changes to the default behaviour of the application, the changes are saved when exiting from QtiPlot.
The first tab is used to change the general options of the application. In the upper part of the tab, the style is the general decoration used for windows, and the font is the general font used for the GUI. If your application has been compiled with several languages supports, you can select it here.
In this tab, you can change the default color for the workspace of the application. you can also choose the background color and the text color for panels, the panels are the Log Window and the Project explorer.