fix valign option.

lib/widget.js

@@ -3741,7 +3741,7 @@ Element.prototype.render = function() {
       } else if (this.valign === 'bottom') {
         visible -= this._clines.length;
       }
-      yi += visible;
+      ci -= visible * (xl - xi);
     }
   }
 

test/widget-valign.js

@@ -0,0 +1,27 @@
+var blessed = require('../')
+  , screen;
+
+screen = blessed.screen({
+  dump: __dirname + '/logs/valign.log',
+  smartCSR: true,
+  autoPadding: false
+});
+
+var box = blessed.box({
+  parent: screen,
+  top: 'center',
+  left: 'center',
+  width: '50%',
+  height: 5,
+  align: 'center',
+  valign: 'middle',
+  // valign: 'bottom',
+  content: 'Foobar.',
+  border: 'line'
+});
+
+screen.key('q', function() {
+  return process.exit(0);
+});
+
+screen.render();