Ah, there is a small mistake, "if(x>=768/2){" should be "if(x<=768/2){". The difference is that left and right part of titlebar are switched.
Here is the the corrected binary. I seems somehow got confused. You can try both of them.
Added:
Ideally, clicking on the left half will goto top-menu, but in fact there is some slight discrepency. For example, suppose I am under /MMC/books/test, clicking on the left half will take me to /MMC. In /MMC, clicking on the right half will take me to top-menu.
Agian, suppose I am under /MMC/books/test, clicking on the right half will take me to /MMC/books.
Hope the description is clear for you to understand.