Not response to close request

[Mahmoud Mabrok Fouad]

sometimes when i click close and conform Alert it not response and program not close
only by TaskManager

[Mahmoud Mabrok Fouad]

i solved the problem of not close window , by handle exception (NullPointerException) , but still
problem of not load Home screen .

[Ahmed Elzoughby]

this may be be because of another exception.