scroll
fun JTextPane.scrollTextWithLineNumbers(workbench: AvailWorkbench, guideLines: List<Int> = listOf(80)): JLayer<JScrollPane>
Create or look up the JLayer that contains a JScrollPane holding the receiver JTextPane plus a CodeOverlay that manages line numbers as row headers, line guides, and whatever else a CodeOverlay presents.
Return
The requested JLayer.
Parameters
workbench
The owning workbench.
guide
The list of after how many (character) columns to display a guide line. Defaults to a single guideline at 80. Ignored if the receiver has already had this superstructure built for it by a previous call.