Select several elements #gas #sheets

.md

###Select several elements

https://docs.google.com/spreadsheets/d/1H7y_Aoy6pKHUhvXo6EwiYuNKl-7oe9Zyl7mN3QYRIPk/edit?usp=sharing Copy the project here http://goo.gl/LxGXfU Disscussion http://goo.gl/UWi1ee http://www.youtube.com/watch?v=dm4z9l26O0I

Code.gs

function onOpen(e) {
  SpreadsheetApp.getUi()
  .createMenu('Custom Menu')
  .addItem('Show dialog', 'showDialog')
  .addToUi();
}
function showDialog() {  
  var html = HtmlService.createTemplateFromFile('Page').evaluate();
  SpreadsheetApp.getUi()
  .showSidebar(html);
}
var valid = function(){
  try{
    return SpreadsheetApp.getActiveRange().getDataValidation().getCriteriaValues()[0].getValues();
  }catch(e){
    return null
  }
}
function fillCell(e){
  var s = [];
  for(var i in e){
    if(i.substr(0, 2) == 'ch') s.push(e[i]);
  }
  if(s.length) SpreadsheetApp.getActiveRange().setValue(s.join(', '));
}

Page.html

<div>
<? var data = valid(); ?>
<form id="form" name="form">
<? if(Object.prototype.toString.call(data) === '[object Array]') { ?>
<? for (var i = 0; i < data.length; i++) { ?>
<? for (var j = 0; j < data[i].length; j++) { ?>
<input type="checkbox" id="ch<?= '' + i + j ?>" name="ch<?= '' + i + j ?>" value="<?= data[i][j] ?>"><?= data[i][j] ?><br>
<? } ?>
<? } ?>
<? } else { ?>
<p>May be current cell havn't the <a href="https://support.google.com/drive/answer/139705?hl=en">Data validation...</a></p>
<? } ?>
<input type="button" value="fill current" onclick="google.script.run.fillCell(this.parentNode)" />
<input type="button" value="get validation from current" onclick="google.script.run.showDialog()" />
</form>
</div>

This really nice!

A couple questions...
1- If I wanted to add an input like "Discard" that effectively closes Page.html the way that the system "X" does in the top right corner, what would I set as the onClick event?

input type="button" value="Discard" onclick="..." />

2- When the ShowDialog is fired, any ideas on how the values already in the cell could be used to pre-check options shown in the Page.html? Let's say that my validation list of values is: blue, red, yellow, green and cell B3 contains "blue,green" when I invoke the Custom Menu / showdialog, I'd want blue and green to be checked and red and yellow to be unchecked.

Thanks!