Drag item > Right-click to open context menu > Item sticks to cursor

[adam-marshall]

1. Go to https://tiberiuzuld.github.io/angular-gridster2/
2. Left click and hold on an item
3. Start dragging it somewhere
4. Right click - context menu appears whilst dragging
5. Left click - to close context menu

Outcome: the item is still being dragged, but the user has released the left mouse button, the item is permanently attached.

Workaround: refresh the page.

Any suggestions?