Qt: windows functions are unresolved external symbols - c++

Question

I'm trying to compile a simple helloworld-like non-Qt C++ application using te WinAPI in QtCreator. Here's the code:
#include <windows.h>
int main()
{
HWND cons = GetConsoleWindow();
SetWindowText(cons, L"I am the console window");
MessageBox(cons, L"Hello world!", L"I am the MessageBox", MB_OK | MB_ICONERROR);
return 0;
}
Looks very simple, but when I've tried to build it, the compilation fails with:
main.obj:-1: error: LNK2019: unresolved external symbol __imp__MessageBoxW#16 referenced in function _main
main.obj:-1: error: LNK2019: unresolved external symbol __imp__SetWindowTextW#8 referenced in function _main
I started to seek, and I found this, but it wasn't helping me at all, because when I had written this:
LIBS += -L"C:\\Program Files (x86)\\Microsoft SDKs\\Windows\\v7.0A\\Lib"
and even this:
LIBS += -L"C:\\Program Files (x86)\\Microsoft SDKs\\Windows\\v7.0A\\Lib\\shell32.lib"
in my .pro, these "symbols" still stand unresolved. I ran qmake after each change to the .pro-file contents. So, any ideas?

Answer 1

-L sets the search paths for DLLs, but it doesn't actually link anything. The actual linking is done via -l. Setting the search path for system libraries shouldn't be necessary, but you'll need to link against user32:
win32:LIBS += -luser32

Answer 2

Additional to Frank's answer (which helped me very much, thanks for that!) I would like to add that this is only required vor MSVC, MinGW doesn't seem to need that line. Which was for me the most confusing part, I first thought I had problems with the msvc toolchain.
My inclusion now looks like this to reflect this fact:
msvc: LIBS += -luser32