I am currently using the Twitter Bootstrap framework, and when using the modal windows I cannot get over js elements to work like datepicker or validation, though chosen and uniform render correctly. please see my modal window below:
<div class="modal hide in" id="newMember" style="display: block; " aria-hidden="false">
<div class="modal-header">
<button class="close" data-dismiss="modal" type="button">×</button>
<h3>New Member Form</h3>
</div>
<form accept-charset="UTF-8" action="/players" class="form-horizontal" id="new_user" method="post"><div style="margin:0;padding:0;display:inline"><input name="utf8" type="hidden" value="✓"><input name="authenticity_token" type="hidden" value="KdL6cc2Vb53qeMY+PpBUS70myT4HX1uWofMUBolLea8="></div>
<div class="modal-body">
<div class="widget-content nopadding">
<div class="control-group">
<label class="control-label" for="user_role">Role</label>
<div class="controls">
<select id="user_role" name="user[role]" style="display: none; " class="chzn-done"><option value="">Select member role</option>
<option value="1">Player</option>
<option value="2">Coach</option>
<option value="3">Parent</option>
<option value="4">Manager</option>
<option value="5">Non-player</option></select><div id="user_role_chzn" class="chzn-container chzn-container-single" style="width: 222px; "><a href="javascript:void(0)" class="chzn-single"><span>Select member role</span><div><b></b></div></a><div class="chzn-drop" style="left: -9000px; width: 220px; top: 0px; "><div class="chzn-search" style=""><input type="text" autocomplete="off" style="width: 212px; "></div><ul class="chzn-results"><li id="user_role_chzn_o_0" class="active-result result-selected" style="">Select member role</li><li id="user_role_chzn_o_1" class="active-result" style="">Player</li><li id="user_role_chzn_o_2" class="active-result" style="">Coach</li><li id="user_role_chzn_o_3" class="active-result" style="">Parent</li><li id="user_role_chzn_o_4" class="active-result" style="">Manager</li><li id="user_role_chzn_o_5" class="active-result" style="">Non-player</li></ul></div></div>
</div>
</div>
<div class="control-group">
<label class="control-label" for="user_full_name">Full name</label>
<div class="controls">
<input id="user_first_name" name="user[first_name]" placeholder="First Name" size="30" type="text">
</div>
</div>
<div class="control-group">
<label class="control-label" for="user_last_name">Last name</label>
<div class="controls">
<input id="user_last_name" name="user[last_name]" placeholder="Last Name" size="30" type="text">
</div>
</div>
<div class="control-group">
<label class="control-label" for="user_email">Email</label>
<div class="controls">
<input id="user_email" name="user[email]" placeholder="Email Address" size="30" type="text">
</div>
</div>
<div class="control-group">
<label class="control-label" for="user_date_of_birth">Date of birth</label>
<div class="controls">
<input class="datepicker" data-date-format="dd/mm/yyyy" id="user_dob" name="user[dob]" placeholder="dd/mm/yyyy" readonly="readonly" size="30" type="text">
</div>
</div>
<div class="control-group">
<label class="control-label" for="user_gender">Gender</label>
<div class="controls">
<select id="user_gender" name="user[gender]" style="display: none; " class="chzn-done"><option value="">Select gender</option>
<option value="Male">Male</option>
<option value="Female">Female</option></select><div id="user_gender_chzn" class="chzn-container chzn-container-single" style="width: 222px; "><a href="javascript:void(0)" class="chzn-single"><span>Select gender</span><div><b></b></div></a><div class="chzn-drop" style="left: -9000px; width: 220px; top: 0px; "><div class="chzn-search" style=""><input type="text" autocomplete="off" style="width: 212px; "></div><ul class="chzn-results"><li id="user_gender_chzn_o_0" class="active-result result-selected" style="">Select gender</li><li id="user_gender_chzn_o_1" class="active-result" style="">Male</li><li id="user_gender_chzn_o_2" class="active-result" style="">Female</li></ul></div></div>
</div>
</div>
<div class="control-group">
<label class="control-label" for="user_team">Team</label>
<div class="controls">
<select id="user_team_id" name="user[team_id]" style="display: none; " class="chzn-done"><option value="">None</option>
<option value="4">Metro 3 East</option>
<option value="1">State League 3</option>
<option value="2">State League 4</option>
<option value="3">Metro 3 South</option>
<option value="5">Pennant E</option>
<option value="6">Under 9 White</option>
<option value="7">Under 9 Navy</option>
<option value="8">Under 13 Pennant South East</option>
<option value="9">Under 17 Pennant South East</option>
<option value="10">Under 15 South (1)</option>
<option value="11">Under 11 Pennant South East</option>
<option value="12">Under 11 South</option></select><div id="user_team_id_chzn" class="chzn-container chzn-container-single" style="width: 222px; "><a href="javascript:void(0)" class="chzn-single"><span>None</span><div><b></b></div></a><div class="chzn-drop" style="left: -9000px; width: 220px; top: 0px; "><div class="chzn-search" style=""><input type="text" autocomplete="off" style="width: 212px; "></div><ul class="chzn-results"><li id="user_team_id_chzn_o_0" class="active-result result-selected" style="">None</li><li id="user_team_id_chzn_o_1" class="active-result" style="">Metro 3 East</li><li id="user_team_id_chzn_o_2" class="active-result" style="">State League 3</li><li id="user_team_id_chzn_o_3" class="active-result" style="">State League 4</li><li id="user_team_id_chzn_o_4" class="active-result" style="">Metro 3 South</li><li id="user_team_id_chzn_o_5" class="active-result" style="">Pennant E</li><li id="user_team_id_chzn_o_6" class="active-result" style="">Under 9 White</li><li id="user_team_id_chzn_o_7" class="active-result" style="">Under 9 Navy</li><li id="user_team_id_chzn_o_8" class="active-result" style="">Under 13 Pennant South East</li><li id="user_team_id_chzn_o_9" class="active-result" style="">Under 17 Pennant South East</li><li id="user_team_id_chzn_o_10" class="active-result" style="">Under 15 South (1)</li><li id="user_team_id_chzn_o_11" class="active-result" style="">Under 11 Pennant South East</li><li id="user_team_id_chzn_o_12" class="active-result" style="">Under 11 South</li></ul></div></div>
</div>
</div>
<div class="control-group">
<label class="control-label" for="user_mobile">Mobile</label>
<div class="controls">
<input id="user_mobile" maxlength="10" name="user[mobile]" placeholder="i.e 0421813529" size="10" type="tel">
<span class="help-block">
<input name="user[private_mobile]" type="hidden" value="0"><div class="checker" id="uniform-user_private_mobile"><span><div class="checker" id="uniform-user_private_mobile"><span><input id="user_private_mobile" name="user[private_mobile]" type="checkbox" value="1" style="opacity: 0; "></span></div></span></div>
<a href="javascript:void(0)" class="tip-bottom" data-original-title="Normally, all members of the team can see this information. If you don't want teammates to see this information, just click this checkbox. (Note: Team managers will always see this information.)">Private</a>
</span>
</div>
</div>
<div class="control-group">
<label class="control-label" for="user_manager_access">Manager access</label>
<div class="controls">
<input name="user[manager]" type="hidden" value="0"><div class="checker" id="uniform-user_manager"><span><div class="checker" id="uniform-user_manager"><span><input id="user_manager" name="user[manager]" type="checkbox" value="1" style="opacity: 0; "></span></div></span></div>
</div>
</div>
<div class="control-group">
<label class="control-label" for="user_admin_access">Admin access</label>
<div class="controls">
<input name="user[admin]" type="hidden" value="0"><div class="checker" id="uniform-user_admin"><span><div class="checker" id="uniform-user_admin"><span><input id="user_admin" name="user[admin]" type="checkbox" value="1" style="opacity: 0; "></span></div></span></div>
</div>
</div>
</div>
</div>
<div class="modal-footer">
<div class="pull-right">
<input class="btn btn-primary" name="commit" type="submit" value="Create User">
<a class="btn btn-danger" data-dismiss="modal" href="#">Cancel</a>
</div>
</div>
</form>
</div>
add z-index above 1051 in class datepicker
add something like this in page or css
<style>
.datepicker{z-index:1151 !important;}
</style>