dont reverse colors for Button

--it looks better if the Button(s) keep
their color instead to reverse it for the
reversed plasmaextended color scheme

app/plasmathemeextended.cpp

@@ -167,6 +167,7 @@ void PlasmaThemeExtended::updateReversedSchemeValues()
 
     if (normalPtr && reversedPtr) {
         foreach (auto groupName, reversedPtr->groupList()) {
+            if (groupName != "Colors:Button") {
                 KConfigGroup reversedGroup(reversedPtr, groupName);
 
                 if (reversedGroup.keyList().contains("BackgroundNormal")
@@ -180,6 +181,7 @@ void PlasmaThemeExtended::updateReversedSchemeValues()
                     reversedGroup.sync();
                 }
             }
+        }
 
         //! update WM group
         KConfigGroup reversedGroup(reversedPtr, "WM");