A generic function used to distinguish whether only the locations of plots will be used to arrange them in a grob, or whether all arguments to `gridExtra::arrangeGrob()` will be used.
loonGrob_layoutType(target)the (compound) loon plot to be laid out.
either the string "locations" (the default) or the string "arrangeGrobArgs". If "locations", then the generic function `l_getLocations()` will be called and only the location arguments of `gridExtra::arrangeGrob()` used (i.e. a subset of `c("ncol", "nrow", "layout_matrix", "heights", "widths")`). The grobs to be laid out are constructed using the generic function `l_getPlots()`.