WPF gives enormous flexibility in the design of user interfaces -removing the constrains of traditional controls such as plain grey forms, combo boxes, list boxes, and dull buttons. This allows development of interfaces that are both visually appealing and much more intuitive, giving much richer user experiences, in ways that were previously not possible.

Traditional Windows interface technology (called ‘WinAPI’) does allow a certain degree of flexibility in UI design, but it often requires much more development effort to implement radical UI designs, and so developers (and the customers who pay them!) usually opt for more ‘run of the mill’ UIs. This is why Windows applications tend to all look rather similar. In contrast, WPF allows radical and innovative UI designs to be implemented easily.

To illustrate the point, let’s take an example – the tree control. The standard Win API tree control allows only simple text at each node – it doesn’t even support mixed fonts. If the application designer wants to display ‘rich information’ at each node of the tree (e.g. mixed font text plus a graphic) the programmer is forced into a solution such as implementing a separate display pane that updates according to which node is selected in the tree, rather than the ideal of displaying the rich data within the tree control.

WPF, however, has a fundamentally different approach to UI components, based on the so-called ‘lookless UI’. This means that although standard WPF controls look similar to their traditional counterparts, this is only their default behaviour. With WPF it is easy to completely change the look of a control. For example, a tree control can have anything at each node, such as a small panel that contains text and a graphic.

Similarly, a list box in WinAPI can only display text and only in a vertical orientation, whilst a WPF list box can show a list of any type of object (for example a panel containing text, a button and a graphic) in either a horizontal or vertical orientation.

So, whilst the traditional list box is ‘a list of text items displayed, a vertical list and supporting multi-select’, the WPF counterpart is ‘a list of items (of any type) displayed either in a vertical or horizontal list and supporting multi-select’. The WPF list box is said to be ‘lookless’ because the term ‘list box’ refers only to its general behaviour rather than specifically to its appearance.

This is why the flexibility of WPF results in much richer user experiences than is possible with traditional application development tools.