[unity8] launcher, changing icons positions (drag/drop) sometimes leaves the launcher in an awkward state

[dinamic]

ubuntu 17.04 unity8
[unity8] launcher, changing icons positions (drag/drop) sometimes leaves the launcher in an awkward state

have a lot of apps pinned to the launcher (more than one screen so you can scroll)
then start moving the apps positions (drag and drop) apps from the last position (way back down) to the first position (under the ubuntu logo). sometimes after you move an icon the launcher remains faded (in the state of drag i guess) see attached image. and after that if you launch an app from the top it automatically scrolls down

[dinamic (dinamic6661)]

i also see some launcher drag errors in unity8.log

[dinamic (dinamic6661)]

[2017-03-16:09:11:19.477] qml: ItemGrabber: Saving image to /home/pixel/Pictures/Screenshots/screenshot20170316_091119477.png
[2017-03-16:09:11:21.842] file:///usr/share/unity8//Launcher/LauncherPanel.qml:557: TypeError: Cannot read property 'dragging' of undefined
[2017-03-16:09:11:21.858] file:///usr/share/unity8//Launcher/LauncherPanel.qml:557: TypeError: Cannot read property 'dragging' of undefined
[2017-03-16:09:11:21.859] file:///usr/share/unity8//Launcher/LauncherPanel.qml:557: TypeError: Cannot read property 'dragging' of undefined
[2017-03-16:09:11:21.879] file:///usr/share/unity8//Launcher/LauncherPanel.qml:557: TypeError: Cannot read property 'dragging' of undefined
[2017-03-16:09:11:23.277] file:///usr/share/unity8//Launcher/LauncherPanel.qml:557: TypeError: Cannot read property 'dragging' of undefined