Detect window manager using KWindowSystem

[Paulo Lieuthier]

Hello again,

here I'm again trying to use KWindowSystem to the benefit of LXQt. 
Thanks for KF5! =D
I'm now trying to check if there is an active window manager, for 
lxqt-session. That's what I'm doing:

   NETRootInfo rootInfo(QX11Info::connection(), NET::Supported);
   qDebug() << "SupportingWMCheck: " <<
   rootInfo.isSupported(NET::SupportingWMCheck);

That appears to be the correct way to check it, after I examined 
KWindowSystem's source code. It works perfectly with Openbox, but not 
for KWin. I keep getting "true" event after I kill KWin. Is that 
something missing from my code? Or am I really going in the wrong 
direction here?

Thanks in advance.
Paulo Lieuthier