pub fn screen_create_handler(&mut self, screen: Screen<H>) -> bool {
        tracing::trace!("Screen create: {:?}", screen);

        let tag_index = self.state.workspaces.len();
        let tag_len = self.state.tags.len_normal();

        // Only used in tests, where there are multiple screens being created by `Screen::default()`
        // The screen passed to this function should normally already have it's id given in the config serialization.
        let workspace_id = match screen.id {
            None => self.state.workspaces.last().map_or(0, |ws| ws.id) + 1,
            Some(set_id) => set_id,
        };

        let mut new_workspace = Workspace::new(screen.bbox, workspace_id);
        if self.state.workspaces.len() >= tag_len {
            tracing::warn!("The number of workspaces needs to be less than or equal to the number of tags available. No more workspaces will be added.");
        }
        new_workspace.load_config(&self.config);

        // Make sure there are enough tags for this new screen.
        let next_id = if tag_len > tag_index {
            tag_index + 1
        } else {
            // Add a new tag for the workspace.
            self.state.tags.add_new_unlabeled()
        };

        self.state.focus_workspace(&new_workspace); // focus_workspace is called.
        self.state.focus_tag(&next_id);
        new_workspace.show_tag(&next_id);
        self.state.workspaces.push(new_workspace.clone());
        self.state.screens.push(screen);
        self.state.focus_workspace(&new_workspace); // focus_workspace is called again.
        false
    }
`screen_create_handler` is called when the display server sends a
`DisplayEvent::ScreenCreate(screen)` event. This happens at initialization.

Returns `true` if changes need to be rendered.
leftwm-core/src/handlers/screen_create_handler.rs