How to set light theme and how to disable button on click text effect?

[learnbyexample]

1. How to set light theme as the default instead of dark theme? Currently, I'm calling self.action_toggle_dark() at the end of compose(self) method.

2. When a button is clicked, there's a background color applied to the text - 'apple' in the screenshot shown below (and any previous such effect applied to another button is automatically removed). Is there a way to disable such effects - either partially for certain buttons or all of the buttons?

[davep]

1. How to set light theme as the default instead of dark theme? Currently, I'm calling self.action_toggle_dark() at the end of compose(self) method.

The App class has a dark property; you could set that to False, perhaps in an on_mount method of the App.

class LightApp( App[ None ] ):
    """An app that's always light."""

    ....

    def on_mount( self ) -> None:
        """Set up the application on startup."""
        self.dark = False

2. When a button is clicked, there's a background color applied to the text - 'apple' in the screenshot shown below (and any previous such effect applied to another button is automatically removed). Is there a way to disable such effects - either partially for certain buttons or all of the buttons?

This is controlled by the text-style of a Button:focus from CSS. So if you don't like the current style you can do something like:

Button:focus {
    text-style: bold;
}

By default in the Textual code it is:

Button:focus {
    text-style: bold reverse;
}

[learnbyexample]

Thanks a lot! I have a couple of follow ups:

1. Is def on_mount( self ) the recommended way to initialize app settings - like choosing theme, initializing self variables, etc? I've been using def __init__(self): super().__init__() followed by other code as required (did this for tkinter projects before).

2. Is https://textual.textualize.io/guide/CSS/#pseudo-classes the relevant documentation for Button:focus? (found by searching for focus). If already available, could you point me to some more examples that use such features?

[davep]

1. Personally I'd do most app configuration in on_mount as it means all of your widgets will be up and running. In the case of setting dark, I've just tested to be sure and you can't actually set it in __init__ without getting an exception -- presumably because light/dark mode is all about affecting the style of your application and, at that point, there's nothing to style yet. I have code that uses __init__ for some things and on_mount for others and which goes where tends to be a case of "it depends".
2. Yup, that's the right spot in the docs to discover pseudo-classes. You'll find examples of their use throughout the Textual codebase; perhaps a good place to start would be having a read of the examples -- you'll see them used for dictionary and five_by_five.

[learnbyexample]

Thanks!

1. I had first called the theme change in __main__ just before app.run() but that stopped working with the latest version. Then I tried __init__ which failed as you note and then compose() had worked. Which is why I thought I should ask here since I was just trying out things without understanding.

2. I'll check out those examples.