With this feature...
Do this...
shale indicator curve
Select the curve to act as the shale indicator (typically GR, SP, or Delta Phi).
clean rock 
shale value
Type the values for clean rock and shale.
float sand
Select to redraw portions of the sand line.
float shale
Select to redraw portions of the shale line.
auto shale
Select in conjunction with float shale to draw the shale line based on the curve variation.
litho modulation curve
Select the background fill (typically Vsh).
left right modulation value
Type the min max range for the associated lithology
pattern.