>>132
なんかのイベントでてきとーに

var
i,j:integer;
begin
with StringGrid1 do
begin
for i:=Selection.Left to Selection.Right do
begin
for j:=Selection.Top to Selection.Bottom do
begin
Cells[i, j] := 'hoge';
end;
end;
end;
end;

>>133
OnDrawCellで自前で塗りつぶすしかないかな？