improve tooltips during parent selection

Signed-off-by: Michael X. Grey <grey@openrobotics.org>

rmf_site_editor/src/interaction/select/replace_parent_3d.rs

@@ -167,8 +167,6 @@ pub fn replace_parent_3d_find_parent(
         return;
     };
 
-    tooltips.add(Cow::Borrowed("Select new parent"));
-
     let object = *order.request();
     for s in selected.read() {
         // Allow users to signal the choice of parent by means other than clicking
@@ -225,6 +223,12 @@ pub fn replace_parent_3d_find_parent(
         hovered = Some(e);
     }
 
+    if hovered.is_some() {
+        tooltips.add(Cow::Borrowed("Click to select this as the parent"));
+    } else if !ignore_click {
+        tooltips.add(Cow::Borrowed("Click to remove parent"));
+    }
+
     if hovered != hovering.0 {
         hover.send(Hover(hovered));
     }