SSpread.GrayAreaBackColor Property
Sets the background color of the area without cells (gray area) when scrolling beyond the maximum rows and columns of the spreadsheet.
Specify a color constant or #RRGGBB format. The initial value is $STD (light gray).
Example of usage
GrayAreaBackColor = $DBLUE;
GrayAreaBackColor = "#6B818E";
Related Items
BackColor, NoBorder property