+++ This bug was initially created as a clone of Bug #1150452 +++ In bug 1150452 I made some changes to the startAndCompleteDragOperation to make it more robust on different platforms, and also more amenable to implementing bug 1146349 (which makes the native event synthesization async). As a result of this, a limitation was introduced in startAndCompleteDragOperation - on windows, doing a drag from a location back to the same location is not possible. The browser_newtab_drag_drop.js test does such a drag, and so was disabled on Windows. This is a follow-up bug to see if we can resolve this issue and re-enable the test. ni? to ttaubert as per https://bugzilla.mozilla.org/show_bug.cgi?id=1150452#c20