Hello, I'm wondering if there is a way to demonstrate multiple back-gated populations within the same xyplot with smooth=F. For example, we create a gate based upon a previously defined quadrantGate: > rect.eff.cd8.gate <- rectangleGate("PerCP.Cy5.5.A"=c(0, + quadGate.memory.CD8 at boundary[[1]]), "PE.Cy7.A"=c(0, + quadGate.memory.CD8 at boundary[[2]]), filterId="CD8_EFFECTOR") Using xyplot with smooth=FALSE and this gate as the filter, I can create a backgate of sorts into another population as follows: xyplot(`PE.A` ~ `Alexa.Fluor.700.A`, Data(wf[['CD8+']]), filter=rect.eff.cd8.gate, smooth=F, par.strip.text=list(cex=0.7), par.settings= list(gate=list(col="purple", alpha=.3)) ) which appears to overplot the gated cells in purple. This is a nice feature to use once in a while. It would be even nicer if I could overplot several different gates at the same time with different colors. I have tried using the following function in a plot call: > my.panel <- function(x, y, ..., frame, my.filter) + { + panel.xyplot(x, y, ...) + glpolygon(filter(frame, my.filter)) + } or the following which will plot multiple filters as long as all channel names are the same, but complains that channel names do not match when attempting the backgating: > xyplot( `SSC-H` ~ `FSC-H` , data=GvHD[[1]], + panel = function(...) { + panel.xyplot.flowset(...) + glpolygon( Filter1 ) + glpolygon( Filter2 ) + } + ) I have also tried to replace 'glpolygon' with 'gpoints' to no effect. Using a filter.result does not change the situation either. I suspect this is possible to do if one has a better understanding of lattice. Thanks in advance for any suggestions. Aric