void () { if (lineSeparatorPainter != null) { return; } RangeHighlighter highlighter = getHistoryViewer().getMarkupModel() .addRangeHighlighter(null, 0, getDocument().getTextLength(), HighlighterLayer.ADDITIONAL_SYNTAX, HighlighterTargetArea.EXACT_RANGE); highlighter.setGreedyToRight(true); highlighter.setCustomRenderer(renderer); lineSeparatorPainter = highlighter; }