title: Qt cross-platform issue: compiles fine on Windows, linker error on Linux
body: <p>I have some Qt code called "GUI". Via Qt Creator, I am able to compile (using GCC) it without any complaints on Windows. However, when I try to compile it (again using GCC via Qt Creator) on Linux, I get a linker error:</p>
  
  <blockquote>
    <p>collect2: ld returned 1 exit status.</p>
  </blockquote>
  
  <p>The only non-Qt library that I use is the STL's vector library.</p>