I want to show TWO Scene simultaneously in my application.
EDITOR has not any problem. working good. but if I build for window
application show just one scene, how to fix it?
When you build the project, by default, only the first scene on your build order will be loaded as the first displayed scene. If you want to load multiple scene simultaneously, you should load the extra scenes additively on a script, for example in C#:
SceneManager.LoadScene("OtherSceneName", LoadSceneMode.Additive);
However in the editor, as you noticed, you could add two scenes and both loaded and runs normally when you hit "Play". This is just one of the editor's helpful functionality for editing multiple scene. Notice that on project hierarchy, only a single scene is recognized as the "Active scene". The editor behaves as if you loaded the active scene in "Single" mode first, then loaded the others in "Additive" mode.
Ref: https://docs.unity3d.com/ScriptReference/SceneManagement.SceneManager.LoadScene.html