var infNamespace = 'com.change_vision.jude.api.inf'
var PresentationPropertyUtil = Java.type(infNamespace + '.presentation.PresentationPropertyUtil')

getSelectedPresentations().forEach(
    function (presentation) {
        try {
            astah.getTransactionManager().beginTransaction()
            presentation.setProperty(PresentationPropertyUtil.createOperandLengthKey(1), 500)
            astah.getTransactionManager().endTransaction()
        } catch (e) {
            astah.getTransactionManager().abortTransaction()
            throw e
        }    
    }
)

function getSelectedPresentations() {
    var viewManager = astah.getViewManager()
    var diagramViewManager = viewManager.getDiagramViewManager()
    var selectedPresentations = diagramViewManager.getSelectedPresentations()
    return Java.from(selectedPresentations)
}