The basic principle of a toolkit is to provide the application with a set of objects whose default values are to be modified. The MOTIF toolkit is event-based. The application initializes predefined widgets then enters a hang-up loop. Dialog with the outside world is carried out by interruption (mouse click, keyboard ...). Programing is widget oriented; widget trees are defined, and widgets are linked with functions (methods or callbacks). Widgets are like "black boxes" with specific input values (resources) which are likely to provide information.(via callback functions).
