Edit-Box-Region Mode

This mode allows you to apply a one by one cell brush to
a rectangular region of the raster map.

To identify the rectangular region to be edited you must 
move the mouse to one corner of the desired rectangular 
region and press and hold down the left mouse button.  
As you drag the mouse you will notice a box appear on the 
display.  Once the box is sized appropriately, release the 
left mouse button.

You will then be presented with a dialog box that shows the
range of raster map rows and columns that will be effected 
by the edit.  You may edit these values.  If you approve of
the ranges, press the OK button to proceed with the edit, 
otherwise press the Cancel button to abort the edit. 
If you do not approve of the result of the edit operation
use the @ref("Edit-Undo",xgre/edit_undo) menu option immediately to reverse it.
