Why is my button not in the place I write it to be?

So I'm making an interface for an application, and I tried to make a button and "stick it" to the right-bottom of the window, however, it works for the left part (it follows the window when expanded), but the bottom part doesn't work and I dont know why

kivy code:

Screen:
    BoxLayout:
        orientation: 'vertical'
        
        MDTopAppBar:
            id: title_bar
            title: 'Dietas'
            md_bg_color: 0.08,0.07,0.45                     
            specific_text_color: 1,1,1
            left_action_items: [["menu", lambda x: nav_drawer.set_state('toggle')]]
            
        Widget:


    MDNavigationLayout:

        ScreenManager:
            id: scr
            `your text`
            MDScreen:
                name: 'diet_screen'
                MDBoxLayout:

                    orientation: 'vertical'
                    padding: "5dp"
                    pos_hint: {"top": 1}
                    adaptive_height: True
                    
                    MDList:
                        padding: ("11dp", "60dp" , "11dp", "11dp")
                        
            
                        OneLineListItem:
                            text: 'testitem'
                            on_press:         
                             
                    
                    
                    MDRaisedButton:
                        text: "Nueva Dieta"
                        md_bg_color: "white"
                        text_color: "black"
                        font_size: 16.2
                        pos_hint: {"right": 1, "bottom": 1}

        MDNavigationDrawer:
            id: nav_drawer
        
            BoxLayout:
                orientation: 'vertical'
                spacing: '8dp'
                

               
                ScrollView:
                    MDList:

                        OneLineIconListItem:
                            text: 'Usuario'
                            on_press: 
                                scr.current= 'user_screen'
                                title_bar.title = "Usuario"
                                nav_drawer.set_state('close')
                            IconLeftWidgetWithoutTouch:
                                icon: 'descarga.png'
                                on_press: 
                                    scr.current= 'user_screen'
                                    title_bar.title = "Usuario"
                                    nav_drawer.set_state('close')

What happens What it's supposed to happen

I tried to expand the boxlayout but I dont know if that's the problem, and all the pos_hint commands.

Solution

This is due to this line adaptive_height: True, the height is calculated automatically, you can check what area the widget occupies in this way

MDBoxLayout:
    orientation: 'vertical'
    padding: "5dp"
    pos_hint: {"top": 1}
    adaptive_height: True
    canvas:
        Color:
            rgba: [1, 0, 1, 0.5]
        Rectangle:
            pos: self.pos
            size: self.size

A working solution to the problem

from kivymd.app import MDApp
from kivy.lang.builder import Builder

KV = """
Screen:
    BoxLayout:
        orientation: 'vertical'
        
        MDTopAppBar:
            id: title_bar
            title: 'Dietas'
            md_bg_color: 0.08,0.07,0.45                     
            specific_text_color: 1,1,1
            left_action_items: [["menu", lambda x: nav_drawer.set_state('toggle')]]
            
        Widget:

    MDNavigationLayout:

        ScreenManager:
            id: scr
            
            MDScreen:
                name: 'diet_screen'
                
                MDBoxLayout:
                    orientation: 'vertical'
                    padding: "5dp"
                    pos_hint: {"top": 1}
                    adaptive_height: True
                    
                    MDList:
                        id: list
                        padding: ("11dp", "60dp" , "11dp", "11dp")

                        OneLineListItem:
                            text: 'testitem'

                MDRaisedButton:
                    text: "Nueva Dieta"
                    md_bg_color: "white"
                    text_color: "black"
                    font_size: 16.2
                    pos_hint: {"right": 1, "bottom": 1}

        MDNavigationDrawer:
            id: nav_drawer
        
            BoxLayout:
                orientation: 'vertical'
                spacing: '8dp'
               
                ScrollView:
                    MDList:
                        OneLineIconListItem:
                            text: 'Usuario'
                            on_press: 
                                scr.current= 'user_screen'
                                title_bar.title = "Usuario"
                                nav_drawer.set_state('close')
                                
                            IconLeftWidgetWithoutTouch:
                                # icon: 'descarga.png'
                                on_press: 
                                    scr.current= 'user_screen'
                                    title_bar.title = "Usuario"
                                    nav_drawer.set_state('close')
"""


class TestApp(MDApp):
    def build(self):
        self.theme_cls.theme_style = 'Dark'
        return Builder.load_string(KV)


TestApp().run()

Also a good solution to your problem would be to arrange all widgets in MDBoxLayout in this way

MDScreen:
    name: 'diet_screen'
    
    MDBoxLayout:
        orientation: 'vertical'
        
        MDBoxLayout:
            orientation: 'vertical'
            padding: "5dp"
            adaptive_height: True
            
            MDList:
                id: list
                padding: ("11dp", "60dp" , "11dp", "11dp")

                OneLineListItem:
                    text: 'testitem'
                    
        Widget:
            
        MDRaisedButton:
            text: "Nueva Dieta"
            md_bg_color: "white"
            text_color: "black"
            font_size: 16.2
            pos_hint: {"right": 1}