Some of our users are experiencing a problem using the mouse in Firefox, where the mouse appears to "float around" when you are drawing or moving items in Web Editor.
The reason for this is that in Firefox 49.0.2, asynchronous plugin rendering for Flash is now enabled by default. This causes problems with mouse tracking. The problem is described in the following bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1312528
If you experience the problem, please update to the latest version of Firefox where this problem should be fixed.
You can also use Web Editor with another browser or download the RoomSketcher App.