I found the source of the problem but sadly no solution. The source of the problem ist Lollipop 5.X. The OS creates this Floating Menu Buttons. They are no Tool Boxes and have nothing in common with the Toolbox feature of the S5/mini except that they are appearing as floating ball with 3 dots. The floating Menu button appears only in apps which are no stock apps of Lollipop and in old apps which did not replace the former Menu Button function into a 3-dot symbol(mostly in the right upper corner) in app overlay. Lollipop is asking every app at start if it has the 3 dot menu button on the right upper corner, if it has not, lollipop will create a floating menu button. Confusingly, even if some apps have a 3 dot menu button, the floating menu circle still appears. Sadly I cannot find anything to deactivate it, as it is a help mechanism of lollipop to be able to access the menu of any app, including very old ones.