[tui] Add basic support for focusing widgets.

It's pretty bad but it allows to control which widget accepts input.

src/tui/logger.rs

@@ -1,5 +1,5 @@
 use crate::tui::app::{AppComponents, ComponentOf};
-use crate::tui::component::{Action, Component};
+use crate::tui::component::{Action, Component, ComponentState, Focus};
 use ratatui::buffer::Buffer;
 use ratatui::crossterm::event::{Event, KeyCode, KeyEvent};
 use ratatui::layout::Rect;
@@ -11,6 +11,7 @@ use tui_logger::{TuiLoggerLevelOutput, TuiLoggerSmartWidget, TuiWidgetEvent, Tui
 /// The logger is bound to info!, debug!, error!, trace! macros within Tui::new().
 pub struct Logger {
     state: TuiWidgetState,
+    pub(crate) component_state: ComponentState,
 }
 
 impl<'a> ComponentOf<Logger> for AppComponents<'a> {
@@ -32,6 +33,7 @@ impl Logger {
     pub fn new() -> Self {
         Self {
             state: TuiWidgetState::new(),
+            component_state: Default::default(),
         }
     }
 }
@@ -64,6 +66,10 @@ impl Component for Logger {
         "Logger"
     }
 
+    fn is_active(&self) -> bool {
+        self.component_state.focus == Focus::Active
+    }
+
     fn handle_event(&mut self, event: Event) -> anyhow::Result<Action> {
         if let Some(key_event) = event.as_key_event() {
             return self.handle_key_events(key_event);