When the panel toolbox is open, a control handle slides out of any hovered widget. This is fine, but when a different widget is hovered, the handle slides across to the centre of the new widget. This animation is inconsistent, because the slide-out animation and the controls presented indicate that the handle is part of the widget, yet the slide-across animation contradicts this, by suggesting the handle is shared between different widgets. IMO a (fast) slide-in/slide-out at newly hovered widget or a good old fashioned non-animated move are preferable to this inconsistency.
This feature request was filed for KDE Plasma 4, which reached end-of-support status in August 2015. KDE Plasma 5's desktop shell has been almost completely rewritten for better performance and usability, so it is likely that this feature request is already implemented in Plasma 5, or is no longer applicable.
Accordingly, we hope you understand why we must close this feature request. If the requested feature is still desired but not implemented in KDE Plasma 5.12 or later, please feel free to open a new ticket in the "plasmashell" product after reading https://community.kde.org/Get_Involved/Bug_Reporting
If you would like to get involved in KDE's bug triaging effort so that future mass bug closes like this are less likely, please read https://community.kde.org/Get_Involved#Bug_Triaging
Thanks for your understanding!