Wire exact Scenario group selection and contextual admission

crates/oa-desktop/src/behavior/scenario.rs

@@ -7,6 +7,7 @@ use std::{cell::RefCell, collections::BTreeSet};
 mod camera;
 pub(crate) mod focus;
 pub(crate) mod group_reorder;
+pub(crate) mod selection;
 pub(crate) mod spacing;
 use super::scenario_layout::{
     Representation,
@@ -144,6 +145,7 @@ impl std::fmt::Display for CanvasTool {
 }
 #[derive(Debug, Clone)]
 pub enum CanvasEvent {
+    Selection(Box<selection::Event>),
     Spacing(spacing::Event),
     Scrolled(Context, ScrollArea, iced::Vector),
     Restored(Context, Id, ScrollArea, iced::Vector),
@@ -187,6 +189,7 @@ impl CanvasEvent {
     pub fn context(&self) -> Context {
         match self {
             Self::Spacing(event) => event.stamp().context,
+            Self::Selection(event) => event.context,
             Self::Scrolled(context, _, _)
             | Self::Restored(context, ..)
             | Self::Viewport(context, _)