• fix which plasma theme colors are used for buttons when Colors:Plasma Theme is chosen
• do not show buttons that the current window has disabled them, for example a window is NOT Closable; Close button becomes hidden in such case
• hide buttons when the last active maximized window is minimized and there are no other shown windows
• improve configuration window texts
• create a new decoration only when it is really needed
• reduce filesystem trackers for scheme colors files
• use shared decoration between all buttons
• set an object name for the shared decoration in order to be easily identified by KDecoration2 decorations