The programmable brush

Raster map editing is done by use of a programmable brush.
The brush is a rectangular matrix of brush cells which can be 
as small as one by one or as big as seven by seven brush cells.

There are a number of factors that determine how the brush
will effect the raster map these are the @ref("brush category",xgre/brushcat.def)
value, the @ref("brush hotspot",xgre/brushhot.def) and the @ref("brush cell attributes.",xgre/brushatt.def)
Raster map cells that are effected by the brush will be
highlighed with the @ref("brush highlight color.",xgre/brushclr.def)

You can use the @ref("Brush-Category",xgre/brush_cat) menu option to set the brush-
category and the @ref("Brush-Color",xgre/brush_color) menu option to set the brush
highlight color.  The @ref("Brush-Create",xgre/brush_create) menu option can be used to
create a new brush and the @ref("Brush-Edit",xgre/brush_edit) menu option can be used
to edit the current brush.

