1. A computer system for focus navigation of a user interface, comprising: a computing processor; a discrete, directional input device, the discrete, directional input device comprising an input device other than a mouse; and one or more computer-readable media storing computer executable components comprising: a directional focus navigation engine for changing an input focus from a current user interface object in the user interface, the input focus being changed in response to receiving a single, discrete, directional input from the discrete, directional input device; a target candidate selector operably coupled to the directional focus navigation engine for selecting target candidates that are in a traversal direction indicated by the single, discrete, directional input, the target candidates being selected from among one or more user interface objects for receiving the input focus, and the target candidate selector operating to: define a selection region including at least an edge of the current user interface object in the direction of the single, discrete directional input through a parallel edge of a display area; define a baseline region within the selection region and which is a subset of the selection region; and select target candidates that overlap the selection region in the direction of the single, discrete, directional input and only when an edge opposite to the direction of the single, discrete, directional input overlaps the selection region; and a target candidate scorer operably coupled to the directional focus navigation engine for scoring the target candidates selected for receiving the input focus, whereby the scoring of each target candidate is used to select a user interface object to receive input focus in response to the single, discrete, directional input, and wherein scoring the target candidates includes: for all selected target candidates that at least partially overlap the baseline region, scoring them according to their perpendicular distance from an edge of the current user interface object, in a direction parallel to the direction of the single, discrete, directional input; and for all selected target candidates that do not overlap the baseline region, scoring them according to their radial distance from a point on a line partially defining one edge of the baseline region.
1. A computer system for focus navigation of a user interface, comprising: a computing processor; a discrete, directional input device, the discrete, directional input device comprising an input device other than a mouse; and one or more computer-readable media storing computer executable components comprising: a directional focus navigation engine for changing an input focus from a current user interface object in the user interface, the input focus being changed in response to receiving a single, discrete, directional input from the discrete, directional input device; a target candidate selector operably coupled to the directional focus navigation engine for selecting target candidates that are in a traversal direction indicated by the single, discrete, directional input, the target candidates being selected from among one or more user interface objects for receiving the input focus, and the target candidate selector operating to: define a selection region including at least an edge of the current user interface object in the direction of the single, discrete directional input through a parallel edge of a display area; define a baseline region within the selection region and which is a subset of the selection region; and select target candidates that overlap the selection region in the direction of the single, discrete, directional input and only when an edge opposite to the direction of the single, discrete, directional input overlaps the selection region; and a target candidate scorer operably coupled to the directional focus navigation engine for scoring the target candidates selected for receiving the input focus, whereby the scoring of each target candidate is used to select a user interface object to receive input focus in response to the single, discrete, directional input, and wherein scoring the target candidates includes: for all selected target candidates that at least partially overlap the baseline region, scoring them according to their perpendicular distance from an edge of the current user interface object, in a direction parallel to the direction of the single, discrete, directional input; and for all selected target candidates that do not overlap the baseline region, scoring them according to their radial distance from a point on a line partially defining one edge of the baseline region. 6. The system of claim 1 further comprising an input system operably coupled to the directional focus navigation engine for communicating input from the discrete directional input device to the focus navigation engine.