I want my form lay-out to be nice and straight.

It's for the opening-hours of my customer, and he wants something like this:
opening closing
Monday [input] [input]
tuesday [input] [input]

You get the point.

Problem is, with just field grouping, the fields aren't aligned straight in one line (quite ugly)

Anyone got a clue on how to render these fields as in a table?

I've tried "hacking" a table in by editing the labels, but that only ends up with just as skewed fields.

in the ModelAdmin::init....

Requirements::css("mysite/css/modeladminform.css");

mysite/css/modeladminform.css

.MangoFieldGroup {margin-bottom:10px;clear:both;height:55px;}
.MangoFieldGroup .field, .MangoFieldGroup .field label, .MangoFieldGroup .field div{display:block;float:left;clear:none;width:80px;} 

in your dataobject, surrounding the fields to be grouped

$fields->insertBefore(new LiteralField('MangoFieldGroup'.$strStartField,'<div class="MangoFieldGroup">'),$strStartField);
$fields->insertAfter(new LiteralField('MangoFieldGroup'.$strEndField,'</div>'),$strEndField);

not the cleanest of solutions, but it does work :)

It's cleaner then my "solution" in any way, so :D thnx.