X Resources in Brief

The component widgets of an X Window System application each have two names, a class name that identifies its type (e.g., XmText for the Motif text widget) and an instance name (e.g., width, the name of the property that defines the width of the widget on the screen). The class name can be used to set resources for an entire class of widgets (e.g., to make all text widgets have a black background) while the instance name is used for control of individual widgets or properties.

Applications consist of a tree of widgets, each having a class name and an instance name. To specify a resource for a given widget, list the names of the widgets lying between the top widget and the target widget from left to right, separated by periods. In a moderately complicated widget hierarchy, only some of the widgets are of interest; there are intervening widgets that serve uninteresting purposes (such as a base that holds other widgets). A star (*) character can be used as a wildcard to skip such widgets. Another fact to keep in mind is that a given resource specification is interpreted as broadly as possible to apply to any widget matching that description. This allows a very small set of resource specifications to affect a large number of widgets.