## here's the top of your ui.R file
shinyUI(fluidPage(
## custom CSS for 3 column layout (used below for mechanics filter options)
tags$head(
tags$style(HTML("
.multicol {
-webkit-column-count: 3; /* Chrome, Safari, Opera */
-moz-column-count: 3; /* Firefox */
column-count: 3;
}
"))
),
## use the css, assuming your long list of vars comes from global.R
wellPanel(
tags$div(class = "multicol", checkboxGroupInput("foo", choices = your_vars, label = "foo", selected = NULL))
)
))