Fix the selected state for the panel icons in the status bar (#3450)

This PR fixes a bug where the selected state for the panel icons in the
status bar was not correctly reflecting whether the panel was open.

It was erroneously using the `is_open` state for the context menu.

Release Notes:

- N/A

crates/ui2/src/components/stories/icon_button.rs

@@ -14,6 +14,12 @@ impl Render for IconButtonStory {
             .child(Story::title_for::<IconButton>())
             .child(Story::label("Default"))
             .child(div().w_8().child(IconButton::new("icon_a", Icon::Hash)))
+            .child(Story::label("Selected"))
+            .child(
+                div()
+                    .w_8()
+                    .child(IconButton::new("icon_a", Icon::Hash).selected(true)),
+            )
             .child(Story::label("With `on_click`"))
             .child(
                 div()