Hide and show joints in the browser, like other items (#1168)

Fixes #1160.

crates/doc/src/document.rs

@@ -1709,6 +1709,9 @@ pub struct Visibility {
     pub hidden_sketches: Vec<u64>,
     /// Finished sketches shown although a feature uses them.
     pub shown_sketches: Vec<u64>,
+    /// Assembly joints by id: their glyphs are not drawn (they still constrain and move).
+    #[serde(skip_serializing_if = "Vec::is_empty")]
+    pub hidden_joints: Vec<u64>,
 }
 
 impl Visibility {
@@ -1719,6 +1722,7 @@ impl Visibility {
             && self.hidden_origin.is_empty()
             && self.hidden_sketches.is_empty()
             && self.shown_sketches.is_empty()
+            && self.hidden_joints.is_empty()
     }
 }
 

crates/doc/src/format.rs

@@ -150,6 +150,9 @@
 //!   Associative, editable sketch patterns (`patterns` in a sketch) and their point/radius
 //!   relations are also first saved in 20. Old sketch copies stay independent: migration cannot
 //!   infer which curves formed a pattern.
+//!   The saved visibility can also list hidden assembly joints (`visibility.hidden_joints`,
+//!   joint ids): their glyphs aren't drawn, but they still constrain and drive the parts. A
+//!   design without it shows every joint, as it always did; 0.10.0 would show them all.
 
 use serde_json::Value;