collapse="grid": the empty row and group are both gone
0
1
2
3
4
-0.5
0
0.5
1
panel 0
0
1
2
3
4
-1
-0.5
0
0.5
1
panel 1
0
1
2
3
4
-1
-0.5
0
0.5
1
panel 2
0
1
2
3
4
-1
-0.5
0
0.5
1
panel 3
0
1
2
3
4
-1
-0.5
0
0.5
1
panel 4
0
1
2
3
4
-1
-0.5
0
0.5
1
panel 5
collapse="grid": the empty row and group are both gone