GLUI provides limited control on positioning elements within a panel. By default, the elements are built one after the other in the vertical direction. We can add some styling through the use of horizontal separators (lines). We use one in this example to separate the spinner box from the push button. The call to add_separator_to_panel requires the pointer to the panel, which, in this case, is mainPanel.

Although we do not use any in our examples, it is possible to add columns to a control panel. The GLUI function that adds a column is add_column_to_panel. In addition to passing the panel pointer as the first parameter, we pass a boolean value where true means include a vertical bar and false means do not include the bar.