private int calcOffset(int col, int lineNumber, int lineStartOffset) {
    if (myDocumentWindow.getTextLength() == 0) return 0;

    int end = myDocumentWindow.getLineEndOffset(lineNumber);

    CharSequence text = myDocumentWindow.getCharsSequence();
    return EditorUtil.calcOffset(
        this, text, lineStartOffset, end, col, EditorUtil.getTabSize(myDelegate), null);
  }