I typically have 20 emacs instances open at once, but all but 1 or 2 are minimized. In OpenSUSE 13.2 (KDE 4), minimized instances of an app are shown as greyed out in Panel, so it's immediately obvious which ones I want to interact with. In OpenSUSE Leap 42.2 (KDE Plasma 5.8.3/Framework 5.26.0/64-bit), all app instances under the main app icon are shown identically - none are greyed out ever, which is crippling. I have to manually click on each one because minimized instance aren't greyed out - this is a huge waste of time.
Whether it is minimised or not is exposed to the theme, you'll notice you have a small grey bar above the task if the window is visible, and not if it is minimsed. You might find another theme displays this in a more obvious manner. Minimised windows should *not* be greyed out as they're the ones people more likely want to find; they're still clickable and greyed out is a UI term for a disabled action. See also 311991
Why then is greyed out the appearance in the default theme for OpenSUSE 13.2 (KDE4)? You may associate being greyed out with disabled, but obviously whoever arranged the appearance with OpenSUSE 13.2 (KDE4) didn't. Would you like a screen shot?