main menu: fix int overflow

Signed-off-by: Frank Villaro-Dixon <frank@villaro-dixon.eu>

src/apps.rs

@@ -8,6 +8,23 @@ pub struct MainMenu {
     pub names: Vec<String>,
 }
 
+impl MainMenu {
+    pub fn selected_name(&self) -> &str {
+        &self.names[self.selected_id]
+    }
+
+    pub fn go_left(&mut self) {
+        if self.selected_id > 0 {
+            self.selected_id -= 1;
+        }
+    }
+    pub fn go_right(&mut self) {
+        if self.selected_id < self.names.len() - 1 {
+            self.selected_id += 1;
+        }
+    }
+}
+
 pub struct AppBase {
     name: String,
     pub main_menu: MainMenu,

src/ui.rs

@@ -44,13 +44,13 @@ impl BeoUi {
             Beo5Event::LeftButtonPressed => {
                 println!("Left button pressed");
                 if let Some(selected_app) = self.current_app_mut() {
-                    selected_app.base_mut().main_menu.selected_id += 1;
+                    selected_app.base_mut().main_menu.go_left();
                 }
             }
             Beo5Event::RightButtonPressed => {
                 println!("Right button pressed");
                 if let Some(selected_app) = self.current_app_mut() {
-                    selected_app.base_mut().main_menu.selected_id -= 1;
+                    selected_app.base_mut().main_menu.go_right();
                 }
             }
             _ => {