toggle ui with Tab, add hsv jitter

engine/app_events.cpp

@@ -185,3 +185,12 @@ bool App::key_char(char key)
     layout[main_id]->update();
     return ret == kEventResult::Consumed;
 }
+
+void App::toggle_ui()
+{
+    static bool fullscreen = false;
+    auto m = layout[main_id]->m_children[0];
+    for (int i = 2; i < m->m_children.size(); i++)
+        m->m_children[i]->m_display = fullscreen;
+    fullscreen = !fullscreen;
+}