I'm running KDE Plasma 5.5.5. I've chosen the "Icons only task manager" taskbar widget, which gets me halfway to the Windows 7 behavior. But when I have several open windows of a single app, I want them to get grouped in one button like they do in Windows 7 and Ubuntu Unity. How can I make it do that?
I've read that for KDE 4 these widgets do it:
But I'm not using KDE 4.