Python Programming for Biology: Bioinformatics and Beyond

Figure 26.1.  User interaction with a program via its graphical interface. Various

concepts involved in the design and operation of a graphical interface are illustrated for a

mock example of a graphical interface window. In general all of the graphical items, or

widgets, are placed within the context of a larger area using some form of geometry

management: here we illustrate with left and right layout areas, which are then subdivided

top to bottom. Some graphical objects, like text labels, are generally static and cannot be

changed by the user. However, others like text boxes (for typing into), buttons (to press),

check boxes (to tick) and pull-down menus (to select within) can be manipulated by the

user via a pointing device and keyboard etc. When a graphical object is manipulated the

underlying program is usually informed of any changes, via a ‘callback’ function, so that it

can respond to the new state, or in other words perform the functionality that the user

expects.