fix call stack overflow on form focusing. fixes #38.

lib/widget.js

@@ -4382,6 +4382,10 @@ Form.prototype.__proto__ = Box.prototype;
 Form.prototype.type = 'form';
 
 Form.prototype._refresh = function() {
+  // XXX Possibly remove this if statement and refresh on every focus.
+  // Also potentially only include *visible* focusable elements.
+  // This would remove the need to check for _selected.visible in previous()
+  // and next().
   if (!this._children) {
     var out = [];
 
@@ -4394,9 +4398,17 @@ Form.prototype._refresh = function() {
   }
 };
 
+Form.prototype._visible = function() {
+  return !!this._children.filter(function(el) {
+    return el.visible;
+  }).length;
+};
+
 Form.prototype.next = function() {
   this._refresh();
 
+  if (!this._visible()) return;
+
   if (!this._selected) {
     this._selected = this._children[0];
     if (!this._selected.visible) return this.next();
@@ -4419,6 +4431,8 @@ Form.prototype.next = function() {
 Form.prototype.previous = function() {
   this._refresh();
 
+  if (!this._visible()) return;
+
   if (!this._selected) {
     this._selected = this._children[this._children.length - 1];
     if (!this._selected.visible) return this.previous();
@@ -4439,11 +4453,13 @@ Form.prototype.previous = function() {
 };
 
 Form.prototype.focusNext = function() {
-  this.next().focus();
+  var next = this.next();
+  if (next) next.focus();
 };
 
 Form.prototype.focusPrevious = function() {
-  this.previous().focus();
+  var previous = this.previous();
+  if (previous) previous.focus();
 };
 
 Form.prototype.resetSelected = function() {
@@ -4452,12 +4468,12 @@ Form.prototype.resetSelected = function() {
 
 Form.prototype.focusFirst = function() {
   this.resetSelected();
-  this.next().focus();
+  this.focusNext();
 };
 
 Form.prototype.focusLast = function() {
   this.resetSelected();
-  this.previous().focus();
+  this.focusPrevious();
 };
 
 Form.prototype.submit = function() {