Dragging inside Qt Quick Drawer

I've attached a app example (zip-File) and a screenshot "DrawerDragDrop"

First a few short info:
There are two Drawer. Both with a grey rectangle as background. The Drawer with the green border overlays the drawer with the blue border. Each drawer contains a ListView with smiley icons. The dragMargin of the drawer with green border is 0 and 0.66 for the drawer with the blue border.

To reproduce:
Please make a Drag an Drop like on the screenshot. For that make a pressAndHold on a red Smiley from the right ListView and try to move the dragged smiley to the left ListView. The move of the dragged item will stop. Maybe at the border of the Drawer with the green border.

If i don't use the both Drawers (only the Rectangles) then Drag an Drop the images between the ListViews works very smooth. But wheter the ListViews are embedded in a Drawer, dragging works very rough. Moving the items stop shortly sometimes. Also if I want to drag over the border of the Drawer the Drag stops shortly.

Additional info:
The smiley-images are loaded as Delegates. Every image is embedded in a rectangle. On the screenshot I've tried to drag drop the top Smiley of the right ListView to left ListView. But the move stops and it's a little power necessary to move it to left. I think it stops at the border of the ListView or border of the Drawer. But I'm not sure

Best regards

Snoopy