gitlabhq/app/assets/javascripts/issues.js

function switchToNewIssue(form){
  $(".issues_content").hide("fade", { direction: "left" }, 150, function(){
    $(".issues_content").after(form);
    $('select#issue_assignee_id').chosen();
    $('select#issue_milestone_id').chosen();
    $("#new_issue_dialog").show("fade", { direction: "right" }, 150);
    $('.top-tabs .add_new').hide();
  });
}

function switchToEditIssue(form){
  $(".issues_content").hide("fade", { direction: "left" }, 150, function(){
    $(".issues_content").after(form);
    $('select#issue_assignee_id').chosen();
    $('select#issue_milestone_id').chosen();
    $("#edit_issue_dialog").show("fade", { direction: "right" }, 150);
    $('.add_new').hide();
  });
}

function switchFromNewIssue(){
  backToIssues();
}

function switchFromEditIssue(){
  backToIssues();
}

function backToIssues(){
  $("#edit_issue_dialog, #new_issue_dialog").hide("fade", { direction: "right" }, 150, function(){
    $(".issues_content").show("fade", { direction: "left" }, 150, function() { 
      $("#edit_issue_dialog").remove();
      $("#new_issue_dialog").remove();
      $('.add_new').show();
    });
  });
}