1990 looks right for a post date ref: https://dblp.org/pid/m/MarkSManasse.html ref: https://onlinelibrary.wiley.com/doi/abs/10.1002/spe.4380201409 It'

1990 looks right for a post date ref: https://dblp.org/pid/m/MarkSManasse.html ref: https://onlinelibrary.wiley.com/doi/abs/10.1002/spe.4380201409 It's a shame it's historical. I was hoping that X had been lurking around all this time and was about to stage a comeback. I have fond memories of Quaterdeck's DESQview/X system.