An application specifies the area boundary when it calls GpiBeginArea. There are two options:
The BA_BOUNDARY value tells the programming interface to draw all outlines of the area primitives within the area bracket, using a line that conforms to the current LINEBUNDLE attributes. If the line attributes have not been changed, the default outline color is black on most displays and printers, and the default line style is solid. An application can change the line color and line styles within the area bracket. The interior of the area primitive is filled with the current pattern.
To prevent the interface from outlining an area, an application can use the BA_NOBOUNDARY flag when calling GpiBeginArea. Only the interior fill pattern is visible. This value most often is used when an area contains many overlapping figures, and the interior lines are not desired.
You could think of this option in terms similar to the outline and fill options discussed with boxes and full arcs. The BA_BOUNDARY value corresponds to DRO_OUTLINEFILL, and BA_NOBOUNDARY, to DRO_FILL. There is no distinct boundary value that corresponds to DRO_OUTLINE, the simple outline. To simulate this effect, OR the BA_NOBOUNDARY value with the appropriate area construction value when calling GpiBeginArea.