It seems the issue with all files being modified was linked to EOL ending (see http://mercurial.selenic.com/wiki/EolExtension ).
I tried (hard) to get both Windows & Mac to agree on line ending by adding a .hgeol and .hgrc on both sides but the request is somehow polluted with +0-0 changes... It should be 'OK' though.
Unfortunately I can not accept this code as there are sponge classes. I would recommend for now that you continue to develop in your own fork until the sponge classes are totally removed. I'm sorry - I should've thought of this sooner but they are licensed under a different license than ControlsFX (ControlsFX is BSD, the sponge classes from OpenJFX are GPL+Classpath).
I am happy to merge this into the default repo (that is, take it out of the wip-spreadsheet branch). I would like a +1 from Eugene first though, and then I will merge. I do not think we should review too deeply in this pull request, instead opting to clean up after the merge is complete, so please keep feedback to anything of a show-stopper nature :-)