Gitako's toggle button is not dragable on Firefox

[EnixCoda]

The toggle button can be dragged alone the left border of window starting from v2.2.0.

The feature is implemented with the HTML5 drag API. But Firefox doesn't provide pointer position information when the element is being dragged. The issue has been existing for over 10 years and does not look like to be resolved soon.

https://bugzilla.mozilla.org/show_bug.cgi?id=505521

[EnixCoda]

Perhaps the current implementation is not following the original intent of the drag API.

Will consider refactoring with PointerEvent APIs.

[EnixCoda]

Done in 193a8f4