columnspan

label .a -text A -relief raised
label .b -text B -relief raised
label .c -text C -relief raised
label .d -text D -relief raised
label .e -text E -relief raised
label .f -text F -relief raised
label .g -text G -relief raised
label .h -text H -relief raised

grid .a -row 0 -column 0 -columnspan 2 -sticky nsew
grid .b -row 0 -column 2 -columnspan 2 -sticky nsew
grid .c .d .e .f -row 1 -sticky nsew
grid .g -row 2 -column 0 -columnspan 2 -sticky nsew
grid .h -row 2 -column 2 -columnspan 2 -sticky nsew