KivyMD when switching between screens the palette and the elevation gets lost

Question

I found that whenever I have multiple screens (managed by the MDScreenManager) and I switch between them, certain properties (the elevation of the cards on the screens, or the changes on the primarly palette) are lost.

1. Run the project:

2. Switch to dark mode (theme and palette changes working fine):

3. Change to the second screen (in dark or light mode, doesn't matter):

4. Come back to the first creen (I already lost the MDCard elevation):

5. When switching between themes, the primarly palette has been lost on the dark mode:

   This is my main.py:

   from kivy.config import Config
   Config.set('graphics', 'fullscreen', 0)
   Config.set('graphics', 'window_state', 'maximized')
   
   from kivymd.app import MDApp
   from kivy.lang import Builder
   from kivymd.uix.screenmanager import MDScreenManager
   from kivymd.uix.screen import MDScreen
   from kivy.core.window import Window
   
   class Home(MDScreen):
       pass
   
   class Settings_1(MDScreen):
       pass
   
   Window.size = (800, 480)
   
   sm = MDScreenManager()
   sm.add_widget(Home(name='home'))
   sm.add_widget(Settings_1(name='settings_1'))
   
   
   class Test(MDApp):
   
       dialog = None
       def build(self):
           self.theme_cls.primary_palette = "Blue"
           self.theme_cls.theme_style = "Light"
           self.theme_cls.theme_style_switch_animation = True
           self.theme_cls.material_style = "M3"
   
           return Builder.load_file('kivy.kv')
   
       def on_checkbox_active(self, value):
           if not value.active:
               self.theme_cls.primary_palette = "Gray"
               self.theme_cls.theme_style = "Dark"
           else:
               self.theme_cls.primary_palette = "Blue"
               self.theme_cls.theme_style = "Light"
           return
   
   
   if __name__ == "__main__":
       print('Starting')
   
       Test().run()
   

   and this the kivy.kv file:

   ScreenManager:
       Home:
       Settings_1:
   
   <Home>:
       name:'home'
       MDCard:
           elevation: 3
           orientation: 'vertical'
           adaptive_height: True
           radius: 20
           pos_hint: {"center_x": .5, "center_y": .5}
           size_hint: 0.3, 0.3
           md_bg_color: app.theme_cls.bg_darkest
           padding: dp(5), dp(10)
           spacing: dp(10)
           MDLabel:
               text: 'Label 1'
               halign: 'center'
               pos_hint: {'center_x': 0.5,'center_y':0.8}
   
           MDSeparator:
   
           MDSwitch:
               active: True
               icon_active: "white-balance-sunny"
               icon_inactive: "moon-waning-crescent"
               on_active: app.on_checkbox_active(self)
               theme_text_color: app.theme_cls.theme_style
               pos_hint: {'center_x': 0.5,'center_y':0.5}
   
           MDSeparator:
   
           MDRectangleFlatButton:
               text: 'Next screen'
               pos_hint: {'center_x': 0.5,'center_y':0.2}
               on_press:
                   root.manager.current ='settings_1'
                   root.manager.transition.direction = 'left'
   
   <Settings_1>:
       name:'settings_1'
   
       MDCard:
           elevation: 3
           orientation: 'vertical'
           adaptive_height: True
           radius: 20
           pos_hint: {"center_x": .5, "center_y": .5}
           size_hint: 0.3, 0.3
           md_bg_color: app.theme_cls.bg_darkest
           padding: dp(5), dp(10)
           spacing: dp(10)
           MDLabel :
               text: 'Label 2'
               halign: 'center'
           MDRectangleFlatButton:
               text: 'Previous screen'
               pos_hint: {'center_x': 0.5,'center_y':0.2}
               on_press:
                   root.manager.current ='home'
                   root.manager.transition.direction = 'right'
   

Answer 1

I had that problem too, turns out that its a bug in kivyMD version 1.1.1, it is solved when I upgraded to version 1.2.0, as recommended in: https://github.com/kivymd/KivyMD/issues/1439#issuecomment-1365039955

BTW, it will demend upgarding to a non-released version of kivy as well (2.2.0.dev0) which was the main difficulty here - as wheels are not available for this version, I had to install some additional GL files for it to work.