Prevent unnecessary full screen redraws

js/term/screen.js

@@ -103,10 +103,12 @@ module.exports = class TermScreen extends EventEmitter {
     const self = this
     this.window = new Proxy(this._window, {
       set (target, key, value, receiver) {
-        target[key] = value
-        self.scheduleSizeUpdate()
-        self.renderer.scheduleDraw(`window:${key}=${value}`)
-        self.emit(`update-window:${key}`, value)
+        if (target[key] !== value) {
+          target[key] = value
+          self.scheduleSizeUpdate()
+          self.renderer.scheduleDraw(`window:${key}=${value}`)
+          self.emit(`update-window:${key}`, value)
+        }
         return true
       }
     })

js/term/screen_renderer.js

@@ -52,6 +52,9 @@ module.exports = class ScreenRenderer {
   resetDrawn () {
     // used to determine if a cell should be redrawn; storing the current state
     // as it is on screen
+    if (this.screen.window && this.screen.window.debug) {
+      console.log('Resetting drawn screen')
+    }
     this.drawnScreen = []
     this.drawnScreenFG = []
     this.drawnScreenBG = []
@@ -81,10 +84,12 @@ module.exports = class ScreenRenderer {
   }
 
   setDefaultColors (fg, bg) {
-    this.defaultFgNum = fg
-    this.defaultBgNum = bg
-    this.resetDrawn()
-    this.scheduleDraw('defaultColors')
+    if (fg !== this.defaultFgNum || bg !== this.defaultBgNum) {
+      this.resetDrawn()
+      this.defaultFgNum = fg
+      this.defaultBgNum = bg
+      this.scheduleDraw('default-colors')
+    }
   }
 
   /**