Output is not proper

The output on my laptop is not proper but on my freinds laptop with the same code; the output is as expected. Really frustrated because of this cause i wote the code twice in two diff projects also i unistalled qt and reinstalled it... Just with one small hope that it will make things proper but still didint work...

I have attached two images... one contains the polgyon which needs colour filling.. and expected output is that polygon is filled completely with colour..

the other image is of actual output which is not expected..

and believe me or not the same code on my freinds laptop works fine... even i have got the code verfied from my college professor ...

Pls help!!!!!