Replace WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL with WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL| WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE when configuring LayoutParams in addToWindowManager() method to allow users to normally use back button.
Replace
WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODALwithWindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL| WindowManager.LayoutParams.FLAG_NOT_FOCUSABLEwhen configuring LayoutParams inaddToWindowManager()method to allow users to normally use back button.