a UWP app window can be dragged around the screen by holding the title bar, my question is how we can enable same feature on whole window? I mean user can grab the app from literally anywhere within the window of that app. and can drag it around the screen with mouse on a PC or any other touch device or pen input on other devices like tablets and surface hub.?
You can override the title bar with:
Window.Current.SetTitleBar(UIElement value);
If the UIElement you set is a hit target, it will behave like the default title bar and allow you to drag.