add focus history.

lib/widget.js

@@ -142,7 +142,8 @@ function Screen(options) {
     bottom: this.bottom = 0
   };
 
-  this.focused = null;
+  //this.focused = null;
+  this.history = [];
   this.clickable = [];
   this.input = [];
   this.grabKeys = false;
@@ -449,6 +450,26 @@ Screen.prototype.focusNext = function() {
   return this.focus(1);
 };
 
+Screen.prototype.focusPush = function(el) {
+  if (this.history.length === 10) {
+    this.history.shift();
+  }
+  this.history.push(el);
+};
+
+Screen.prototype.focusLast =
+Screen.prototype.focusPop = function() {
+  return this.history.pop();
+};
+
+Screen.prototype.__defineGetter__('focused', function() {
+  return this.history[this.history.length-1];
+});
+
+Screen.prototype.__defineSetter__('focused', function(el) {
+  return this.focusPush(el);
+});
+
 Screen.prototype.clearRegion = function(xi, xl, yi, yl) {
   return this.fillRegion(this.dattr, ' ', xi, xl, yi, yl);
 };