Python: tic-tac-toe 2

from guizero import App, Box, Text, Picture, info

app = App(title="Os and Xs", width = 480, height = 320, bg=(204,204,204), layout ="grid")
blank = "25fb.png"
X = "274c.png"
O = "2b55.png"
msquare = [0,2,7,6,9,5,1,4,3,8]
Xmoves=[]
Omoves=[]

def testwin(set,letter):
    total = 0
    if (len(set) == 3):
        for count in range(3):
            total = total+set[count]
    if (len(set) == 4):
        if (set[1]+set[2]+set[3]==15 or set[0]+set[1]+set[3]==15 or set[0]+set[2]+set[3]==15):
            total = 15
    if (len(set) == 5):
        if(set[2]+set[3]+set[4]==15 or set[0]+set[1]+set[4]==15 or set[0]+set[2]+set[4]==15 or set[1]+set[3]+set[4]==15 or set[1]+set[2]+set[4]==15 or set[0]+set[3]+set[4]==15):
            total=15
    if total == 15:
        info("We Have a Winner!",letter+" wins this game!")

def error():
    info("illegal move","Sorry, that box is already taken!")

def move(event_data):
    boxclicked = event_data.widget
    square=boxclicked.master.grid[0]+3*boxclicked.master.grid[1]-2
    if boxclicked.image == blank:
        boxclicked.image= img_turn.image
        if img_turn.image == X:
            Xmoves.append(msquare[square])
            testwin(Xmoves,"X")
            img_turn.image=O
        else:
            Omoves.append(msquare[square])
            testwin(Omoves,"O")
            img_turn.image=X
    else:
        error()

box = [[]]
img_box=[[]]
header = Box(app, width=480, height=20, grid=[0,0,5,1])
for x in range (0,3):
    for y in range (1,4):
        n = x*3+y
        box.append(Box(app,width=72,height=72,border=1, grid=[x,y]))
spacer1 = Box(app,width=181,height=219, grid=[3,1,1,3])
spacer2 = Box(app,width=80, height=146, grid=[4,1,1,2])
turn = Box(app,width=80,height=73,grid=[4,3])
header.bg=(0,0,0)
#spacer1.bg=(255,0,0)
#spacer2.bg=(255,0,0)
txt_header=Text(header,text="Tic-Tac-Toe")
txt_header.text_color=(255,255,255)
txt_spacer2=Text(spacer2,align="bottom",text="Turn:")
img_turn=Picture(turn,O)

for count in range(1,10):
    img_box.append(Picture(box[count],blank))

for count in range(1,10):
    img_box[count].when_clicked = move

app.display()