Hello DaniWeb,

After searching for solution I figured it out.

I just want to share that someone might encounter same problem as mine.

So I add z-index.

.dropdown:hover .dropdown-menu {
    z-index: 999;
    display: block;

That solve the problem.

I'm a terrible in C++ but I solved my problem in this forum.

To receive some solution you should try to post the code from that previous programming challenges and a code you try to solve the problem.