Fix: Lay the non-client view out with the frame view when the appbar changes width

rivet/runtime/windows/src/chromium/view.rs

@@ -39,6 +39,20 @@ impl View {
     }
 }
 
+/// The parent of a live view of the loaded build, when its parent pointer holds a view of the
+/// browser module: an object whose first word points into the module. `None` for a root, an
+/// unreadable place or a build that records no bounds offset.
+pub(crate) unsafe fn parent_of(view: usize) -> Option<usize> {
+    let offset = View::parent_offset(crate::builds::get().layout.view_bounds_offset)?;
+    if !crate::chromium::memory::readable(view.checked_add(offset)?, 8) {
+        return None;
+    }
+    let parent = View::at(view).parent_address(offset);
+    let image = crate::chromium::image::recorded()?;
+    let table = crate::chromium::memory::read_word(parent)?;
+    (table > image.base && table < image.base + image.size).then_some(parent)
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

rivet/runtime/windows/src/features/frame_layout.rs

@@ -1018,6 +1018,11 @@ pub unsafe fn relayout(window: HWND) -> bool {
             let layout_immediately: unsafe extern "system" fn(*mut c_void) =
                 std::mem::transmute(base + bv().layout_immediately);
             layout_immediately(view as *mut c_void);
+            // The non-client view above the frame view gives the client view the bounds the frame
+            // view leaves it, so a new appbar width moves the page only when it lays out too.
+            if let Some(parent) = crate::chromium::view::parent_of(view) {
+                layout_immediately(parent as *mut c_void);
+            }
             true
         }
         None => false,