add screen.realloc() method.

README.md

@@ -390,6 +390,7 @@ The screen on which every other node renders.
   `debug` option was set.
 - __alloc()__ - Allocate a new pending screen buffer and a new output screen
   buffer.
+- __realloc()__ - Reallocate the screen buffers and clear the screen.
 - __draw(start, end)__ - Draw the screen based on the contents of the screen
   buffer.
 - __render()__ - Render all child elements, writing all data to the screen

example/blessed-telnet.js

@@ -31,8 +31,7 @@ var server = telnet.createServer(function(client) {
         screen.terminal = data.value;
       } else {
         // Clear the screen since they may have used `env send [var]`.
-        screen.alloc();
-        screen.clearRegion(0, screen.width, 0, screen.height, true);
+        screen.realloc();
       }
       screen.render();
     }

lib/widgets/screen.js

@@ -691,7 +691,7 @@ Screen.prototype.__defineGetter__('height', function() {
   return this.program.rows;
 });
 
-Screen.prototype.alloc = function() {
+Screen.prototype.alloc = function(dirty) {
   var x, y;
 
   this.lines = [];
@@ -700,7 +700,7 @@ Screen.prototype.alloc = function() {
     for (x = 0; x < this.cols; x++) {
       this.lines[y][x] = [this.dattr, ' '];
     }
-    this.lines[y].dirty = false;
+    this.lines[y].dirty = !!dirty;
   }
 
   this.olines = [];
@@ -714,6 +714,10 @@ Screen.prototype.alloc = function() {
   this.program.clear();
 };
 
+Screen.prototype.realloc = function() {
+  return this.alloc(true);
+};
+
 Screen.prototype.render = function() {
   var self = this;