Merge pull request #1613 from ramox81/codex/sheet-set-manager

Sheet Set Manager, NEWSHEETSET / OPENSHEETSET and sheet set fields, with review fixes.

# Conflicts:
#	Cargo.lock
#	src/app/control/actions.rs
#	src/app/mod.rs
#	src/app/settings.rs
#	src/app/update/dialog.rs
#	src/app/update/file.rs
#	src/app/update/mod.rs
#	src/app/view/mod.rs
#	src/ui/dock.rs
#	src/ui/ribbon/mod.rs
#	src/ui/window/field_dialog.rs
#	src/ui/window/mod.rs

src/scene/mod.rs

@@ -37,6 +37,7 @@ pub use page_setup::{apply_default_page_setup, document_page_setups, rotated_mar
 mod dwg_native_constraints;
 mod entity;
 pub use entity::CreateBlockOptions;
+pub use camera_ops::named_view_center;
 #[cfg(test)]
 mod hatch_boundary;
 mod group_layer;
@@ -4561,6 +4562,22 @@ impl Scene {
         self.current_layout_block_handle()
     }
 
+    /// A unique id for a new viewport on the current layout: one past the
+    /// largest id there, at least 2 (1 is the layout's own paper viewport).
+    pub fn next_viewport_id(&self) -> i16 {
+        let layout_block = self.current_layout_block_handle();
+        let max_id = self
+            .document
+            .entities()
+            .filter_map(|e| match e {
+                codec::EntityType::Viewport(v) if v.common.owner_handle == layout_block => Some(v.id),
+                _ => None,
+            })
+            .max()
+            .unwrap_or(1);
+        (max_id + 1).max(2)
+    }
+
     /// True when an entity belongs to the active layout, including imported
     /// DXF entities whose owner handle is NULL but whose BlockRecord still
     /// lists the entity. Keep command validation aligned with the same