Selecting an editing mode

There are a number of different ways to use the brush to edit
a raster map.  However, before you can start editing you must
first unlock the editor.  You can do this by using the @ref("Edit-Unlock",xgre/edit_unlock)
menu option or by clicking on the padlock button on the buttonbar.
When you unlock the editor you will notice that the mode will
change from @ref("Edit-Locked mode",xgre/mode_locked) to @ref("Edit-Normal mode,",xgre/mode_normal) the padlock symbol on
the buttonbar will appear to unlock and the brush cursor will
change into a paintbrush-like icon whenever it enters the
raster map display area.

In Edit-Normal mode you can apply the brush once by pressing and
releasing the left mouse button.  You can also hold down the
left mouse button and drag the brush accross the raster map
to edit a series of cells.

If you wish to edit cells along a straight horizontal line you
should use the Edit-Constrain-Horizontal menu option to set 
@ref("Edit-Constrain-Horizontal mode.",xgre/mode_horiz)

If you wish to edit cells along a straight vertical line you
should use the Edit-Constrain-Vertical menu option to set 
@ref("Edit-Constrain-Vertical mode.",xgre/mode_verti)

If you wish to apply a one by one cell brush to a rectangular area
of raster map cells use the Edit-Box-Region menu option to set
@ref("Edit-Box-Region mode.",xgre/mode_box)

If you wish to apply a one by one cell brush to a polygonal area
of raster map cells use the Edit-Polygon-Region menu option to set
@ref("Edit-Polygon-Region mode.",xgre/mode_poly)


