-hello, I need to create a list of Colors, and I like do this:

list_colors <- varGet vColors
....
color_red  <- checkBox p [text := "Red",  checked := False, on command := do aux red list_colors ]
....
where
   aux one_color list_colors =
     if (elem one_color list_colors)
     then do
        varSet vColors (delete one_color list_colors)
     else do
        varSet vColors (red:list_colors)

but the variable vColors no change and I can not create de list of colors.

Thanks