var subDocument = richEdit.selection.activeSubDocument;
var position = richEdit.selection.active;
var paragraph = subDocument.insertParagraph(position);

var subDocument = richEdit.selection.activeSubDocument;
var position = richEdit.selection.active;

richEdit.history.beginTransaction();
richEdit.beginUpdate();  
var textInterval = subDocument.insertText(position, "Centered text");
subDocument.paragraphs.find(textInterval).forEach(function (paragraph) {
    paragraph.properties = { 
        alignment: DevExpress.RichEdit.ParagraphAlignment.Center,
    }; 
});
richEdit.endUpdate();  
richEdit.history.endTransaction();