"Global" legend with multiple slice series in "row" layout?

[gdevenyi]

From the wonderful MRIcrotome examples I can generate this vertical multi-slice series image:

sliceSeries(nrow = 5, ncol= 1, begin = 25 + 20, end = 298 - 10, dimension = 2) %>%  #slice sequence to display stats
  anatomy(anatVol, low=1, high=5.9) %>%
  overlay(mincArray(model, predictor),     # specify which column of the mincLM model
    low=round(thresholds["0.05",predictor],digits=2), high=round(thresholds["0.01",predictor],digits=2), symmetric = T, alpha=0.6) %>%       # t score range; symmetric = T means show positive and negative t values
  sliceSeries(nrow = 5, ncol= 1, begin = 24 + 15, end = 246 - 10, dimension = 1) %>%  #slice sequence to display stats
  anatomy(anatVol, low=1, high=5.9) %>%
  overlay(mincArray(model, predictor),     # specify which column of the mincLM model
    low=round(thresholds["0.05",predictor],digits=2), high=round(thresholds["0.01",predictor],digits=2), symmetric = T, alpha=0.6) %>%       # t score range; symmetric = T means show positive and negative t values
  sliceSeries(nrow = 5, ncol= 1, begin = 32 + 30, end = 252 - 20, dimension = 3) %>%  #slice sequence to display stats
  anatomy(anatVol, low=1, high=5.9) %>%
  overlay(mincArray(model, predictor),     # specify which column of the mincLM model
    low=round(thresholds["0.05",predictor],digits=2), high=round(thresholds["0.01",predictor],digits=2), symmetric = T, alpha=0.6) %>%   
  legend(predictor) %>%
  draw()

However if I switch to "row" layout, swapping row and column count and forcing row with layout="row"

sliceSeries(nrow = 1, ncol= 5, begin = 25 + 20, end = 298 - 10, dimension = 2) %>%  #slice sequence to display stats
  anatomy(anatVol, low=1, high=5.9) %>%
  overlay(mincArray(model, predictor),     # specify which column of the mincLM model
    low=round(thresholds["0.05",predictor],digits=2), high=round(thresholds["0.01",predictor],digits=2), symmetric = T, alpha=0.6) %>%       # t score range; symmetric = T means show positive and negative t values
  sliceSeries(nrow = 1, ncol= 5, begin = 24 + 15, end = 246 - 10, dimension = 1) %>%  #slice sequence to display stats
  anatomy(anatVol, low=1, high=5.9) %>%
  overlay(mincArray(model, predictor),     # specify which column of the mincLM model
    low=round(thresholds["0.05",predictor],digits=2), high=round(thresholds["0.01",predictor],digits=2), symmetric = T, alpha=0.6) %>%       # t score range; symmetric = T means show positive and negative t values
  sliceSeries(nrow = 1, ncol= 5, begin = 32 + 30, end = 252 - 20, dimension = 3) %>%  #slice sequence to display stats
  anatomy(anatVol, low=1, high=5.9) %>%
  overlay(mincArray(model, predictor),     # specify which column of the mincLM model
    low=round(thresholds["0.05",predictor],digits=2), high=round(thresholds["0.01",predictor],digits=2), symmetric = T, alpha=0.6) %>%   
  legend(predictor) %>%
  draw(layout = "row")

I get a colourbar on just the last sliceseries:

Is it possible to get a global colourbar from this?