I use a custom module which makes heavy use of the Forms API to do mathematical calculations.
The form which you can see at http://linsenrechner.de/node/27 is rendered with the #states attribute. each line uses a container to display two fields. When these fields are filled, a new line should appear.
This works perfect, BEFORE the calculation button is pressed and the ajax request is done.
After this, the behaviour of the form changes: When two fields of a specific line are filled not only one new line appears. In this case, all lines, which are defined in the form, appear at the same time.
The author of the custom module, sukr_s (http://drupal.org/user/554988) wasn't able to exactly locate the bug, but believes it's in states.js
Here are the form arrays, which are used to create the form at http://linsenrechner.de/node/27
$form['container0'] = array(
'#type' => 'container',
'#weight' => -53,
);
$form['container0']['markup0'] = array(
'#weight' => -52,
'#markup' => "<div id='ocalc_header_33'></div>
<div id='ocalc_header_33'>$ocalc_sag_height</div>
<div id='ocalc_header_33'>$ocalc_zone</div>",
);
$form['container0'][$wrapper]['sag0'] = array(
'#type' => 'textfield',
'#title' => $ocalc_sag_height." 0",
'#title_display' => 'invisible',
'#weight' => -51,
'#maxlength' => 4,
'#size' => 4,
'#prefix' => "<div class='form-item-sag0'>$ocalc_zone 0</div>",
'#field_suffix' => "mm",
);
$form['container0'][$wrapper]['zone0'] = array(
'#type' => 'textfield',
'#title' => $ocalc_zone." 0",
'#title_display' => 'invisible',
'#weight' => -50,
'#maxlength' => 4,
'#size' => 4,
'#field_suffix' => "mm",
);
$form['container1'] = array(
'#type' => 'container',
'#weight' => -43,
'#states' => array('visible' => array(
':input[name=sag0]' => array ('filled' => TRUE),
':input[name=zone0]' => array ('filled' => TRUE),
),
),
);
$form['container1'][$wrapper]['sag1'] = array(
'#type' => 'textfield',
'#title' => $ocalc_sag_height." 1",
'#title_display' => 'invisible',
'#weight' => -42,
'#maxlength' => 4,
'#size' => 4,
'#field_suffix' => "mm",
'#prefix' => "<div class='form-item-sag1'>$ocalc_zone 1</div>",
);
$form['container1'][$wrapper]['zone1'] = array(
'#type' => 'textfield',
'#title' => $ocalc_zone." 1",
'#title_display' => 'invisible',
'#weight' => -41,
'#maxlength' => 4,
'#size' => 4,
'#field_suffix' => "mm",
);
$form['container2'] = array(
'#type' => 'container',
'#weight' => -33,
'#states' => array('visible' => array(
':input[name=sag0]' => array ('filled' => TRUE),
':input[name=zone0]' => array ('filled' => TRUE),
':input[name=sag1]' => array ('filled' => TRUE),
':input[name=zone1]' => array ('filled' => TRUE),
),
),
);
$form['container2'][$wrapper]['sag2'] = array(
'#type' => 'textfield',
'#title' => $ocalc_sag_height." 2",
'#title_display' => 'invisible',
'#weight' => -32,
'#maxlength' => 4,
'#size' => 4,
'#field_suffix' => "mm",
'#prefix' => "<div class='form-item-sag1'>$ocalc_zone 2</div>",
);
$form['container2'][$wrapper]['zone2'] = array(
'#type' => 'textfield',
'#title' => $ocalc_zone." 2",
'#title_display' => 'invisible',
'#weight' => -31,
'#maxlength' => 4,
'#size' => 4,
'#field_suffix' => "mm",
);
$form['container3'] = array(
'#type' => 'container',
'#weight' => -23,
'#states' => array('visible' => array(
':input[name=sag0]' => array ('filled' => TRUE),
':input[name=zone0]' => array ('filled' => TRUE),
':input[name=sag1]' => array ('filled' => TRUE),
':input[name=zone1]' => array ('filled' => TRUE),
':input[name=sag2]' => array ('filled' => TRUE),
':input[name=zone2]' => array ('filled' => TRUE),
),
),
);
$form['container3'][$wrapper]['sag3'] = array(
'#type' => 'textfield',
'#title' => $ocalc_sag_height." 3",
'#title_display' => 'invisible',
'#weight' => -22,
'#maxlength' => 4,
'#size' => 4,
'#field_suffix' => "mm",
'#prefix' => "<div class='form-item-sag1'>$ocalc_zone 3</div>",
);
$form['container3'][$wrapper]['zone3'] = array(
'#type' => 'textfield',
'#title' => $ocalc_zone." 3",
'#title_display' => 'invisible',
'#weight' => -21,
'#maxlength' => 4,
'#size' => 4,
'#field_suffix' => "mm",
);
$form['container4'] = array(
'#type' => 'container',
'#weight' => -13,
'#states' => array('visible' => array(
':input[name=sag0]' => array ('filled' => TRUE),
':input[name=zone0]' => array ('filled' => TRUE),
':input[name=sag1]' => array ('filled' => TRUE),
':input[name=zone1]' => array ('filled' => TRUE),
':input[name=sag2]' => array ('filled' => TRUE),
':input[name=zone2]' => array ('filled' => TRUE),
':input[name=sag3]' => array ('filled' => TRUE),
':input[name=zone3]' => array ('filled' => TRUE),
),
),
);
$form['container4'][$wrapper]['sag4'] = array(
'#type' => 'textfield',
'#title' => $ocalc_sag_height." 4",
'#title_display' => 'invisible',
'#weight' => -12,
'#maxlength' => 4,
'#size' => 4,
'#field_suffix' => "mm",
'#prefix' => "<div class='form-item-sag1'>$ocalc_zone 4</div>",
);
$form['container4'][$wrapper]['zone4'] = array(
'#type' => 'textfield',
'#title' => $ocalc_zone." 4",
'#title_display' => 'invisible',
'#weight' => -11,
'#maxlength' => 4,
'#size' => 4,
'#field_suffix' => "mm",
);
