optimize memu hiding

app/src/main/java/com/lizongying/mytv/MainActivity.kt

@@ -105,8 +105,10 @@ class MainActivity : FragmentActivity() {
     }
 
     private val hideRunnable = Runnable {
+        if (!mainFragment.isHidden) {
             supportFragmentManager.beginTransaction().hide(mainFragment).commit()
         }
+    }
 
     private fun mainFragmentIsHidden(): Boolean {
         return mainFragment.isHidden