feat(form): added errorfocus option to focus first error field or dom node

This PR adds a new option errorFocus (default false to stay backward compatible).
When set to true, the first found error field will be focussed ready to immediatly change the values.
When set to a string, it will be used as a dom selector to be able to focus anything else (most probably the error message box)

Until now the user always had to click into the related field before

Author: lubber-de

src/definitions/behaviors/form.js

@@ -1209,6 +1209,24 @@ $.fn.form = function(parameters) {
               if(event && $module.data('moduleApi') !== undefined) {
                 event.stopImmediatePropagation();
               }
+              if(settings.errorFocus) {
+                var focusElement, hasTabIndex = true;
+                if (typeof settings.errorFocus === 'string') {
+                  focusElement = $(settings.errorFocus);
+                  hasTabIndex = focusElement.is('[tabindex]');
+                  // to be able to focus/scroll into non input elements we need a tabindex
+                  if (!hasTabIndex) {
+                    focusElement.attr('tabindex',-1);
+                  }
+                } else {
+                  focusElement = $group.filter('.' + className.error).first().find(selector.field);
+                }
+                focusElement.focus();
+                // only remove tabindex if it was dynamically created above
+                if (!hasTabIndex){
+                  focusElement.removeAttr('tabindex');
+                }
+              }
               if(ignoreCallbacks !== true) {
                 return settings.onFailure.call(element, formErrors, values);
               }
@@ -1514,6 +1532,7 @@ $.fn.form.settings = {
 
   autoCheckRequired : false,
   preventLeaving    : false,
+  errorFocus        : false,
   dateHandling      : 'date', // 'date', 'input', 'formatter'
 
   onValid           : function() {},