raylib: update experimental mode homescreen button (#36344)

* update homescreen exp mode button

* and here

* Apply suggestions from code review

selfdrive/ui/layouts/home.py

@@ -62,6 +62,7 @@ class HomeLayout(Widget):
     self._setup_callbacks()
 
   def show_event(self):
+    self._exp_mode_button.show_event()
     self.last_refresh = time.monotonic()
     self._refresh()
 
@@ -76,6 +77,9 @@ class HomeLayout(Widget):
   def _set_state(self, state: HomeLayoutState):
     # propagate show/hide events
     if state != self.current_state:
+      if state == HomeLayoutState.HOME:
+        self._exp_mode_button.show_event()
+
       if state in self._layout_widgets:
         self._layout_widgets[state].show_event()
       if self.current_state in self._layout_widgets:

selfdrive/ui/widgets/exp_mode_button.py

@@ -18,6 +18,9 @@ class ExperimentalModeButton(Widget):
     self.chill_pixmap = gui_app.texture("icons/couch.png", self.img_width, self.img_width)
     self.experimental_pixmap = gui_app.texture("icons/experimental_grey.png", self.img_width, self.img_width)
 
+  def show_event(self):
+    self.experimental_mode = self.params.get_bool("ExperimentalMode")
+
   def _get_gradient_colors(self):
     alpha = 0xCC if self.is_pressed else 0xFF