diff --git a/src/frontend/src/components/AdvancedFilters.tsx b/src/frontend/src/components/AdvancedFilters.tsx
index 0eb22953..f9f7f733 100644
--- a/src/frontend/src/components/AdvancedFilters.tsx
+++ b/src/frontend/src/components/AdvancedFilters.tsx
@@ -131,7 +131,10 @@ export const AdvancedFilters = ({
   const wrapperClassName = formClassName ? 'px-2' : 'px-2 lg:ml-16 lg:w-[calc(50vw+4rem)]';
 
   const settingsForm = (
-    <div className={wrapperClassName}>
+    <div
+      className={wrapperClassName}
+      onMouseDown={(e) => e.stopPropagation()}
+    >
       {onClose && (
         <div className="mb-1 flex justify-end">
           <button
diff --git a/tests/frontend/test_search_menu_dismiss.py b/tests/frontend/test_search_menu_dismiss.py
new file mode 100644
index 00000000..eaee7c06
--- /dev/null
+++ b/tests/frontend/test_search_menu_dismiss.py
@@ -0,0 +1,94 @@
+"""
+Tests for frontend search menu behavior.
+
+These tests verify that the search menu dismissal logic works correctly,
+particularly that clicking on the AdvancedFilters panel does not close
+the main search menu (issue #1301).
+"""
+
+import os
+from pathlib import Path
+
+import pytest
+
+# Path to the frontend source code
+FRONTEND_SRC_DIR = Path(__file__).parent.parent.parent / "src" / "frontend" / "src"
+
+
+class TestSearchMenuDismiss:
+    """Test that the search menu dismissal behavior is correct."""
+
+    def test_advanced_filters_prevents_mousedown_bubbling(self):
+        """
+        Verify that AdvancedFilters prevents mousedown events from bubbling
+        to the document level, which would otherwise close the main search menu.
+
+        This is the fix for issue #1301: when clicking on dropdown options
+        inside AdvancedFilters, the main search menu was collapsing because
+        the mousedown event bubbled up to the document and triggered the
+        useDismiss hook.
+
+        The fix adds onMouseDown={(e) => e.stopPropagation()} to the
+        AdvancedFilters container div.
+        """
+        advanced_filters_path = FRONTEND_SRC_DIR / "components" / "AdvancedFilters.tsx"
+
+        # Read the component source
+        source_code = advanced_filters_path.read_text()
+
+        # Verify that the onMouseDown stopPropagation handler is present
+        # This prevents the mousedown event from bubbling up to the document
+        # and triggering the useDismiss hook in SearchBar
+        assert (
+            "onMouseDown={(e) => e.stopPropagation()}" in source_code
+        ), (
+            "AdvancedFilters must prevent mousedown events from bubbling up "
+            "to the document. Without this, clicking on dropdown options inside "
+            "AdvancedFilters will close the main search menu (issue #1301)."
+        )
+
+    def test_advanced_filters_container_has_onmousedown(self):
+        """
+        Verify that the settingsForm div in AdvancedFilters has the
+        onMouseDown handler to prevent event bubbling.
+        """
+        advanced_filters_path = FRONTEND_SRC_DIR / "components" / "AdvancedFilters.tsx"
+        source_code = advanced_filters_path.read_text()
+
+        # The settingsForm div should have onMouseDown handler
+        # Check that the div has both className and onMouseDown
+        assert "const settingsForm = (" in source_code, (
+            "AdvancedFilters should define settingsForm as a JSX element"
+        )
+
+        # Verify the onMouseDown is on the settingsForm div (not nested inside another element)
+        # by checking that it appears after the settingsForm declaration
+        settings_form_start = source_code.find("const settingsForm = (")
+        onmousedown_pos = source_code.find("onMouseDown={(e) => e.stopPropagation()}")
+
+        assert settings_form_start != -1, "settingsForm declaration not found"
+        assert onmousedown_pos != -1, "onMouseDown handler not found"
+        assert onmousedown_pos > settings_form_start, (
+            "onMouseDown handler should be inside the settingsForm div"
+        )
+
+    def test_searchbar_uses_usedismiss_for_menu_closing(self):
+        """
+        Verify that SearchBar uses useDismiss to close the main menu
+        when clicking outside the controlled refs.
+        """
+        search_bar_path = FRONTEND_SRC_DIR / "components" / "SearchBar.tsx"
+        source_code = search_bar_path.read_text()
+
+        # SearchBar should use useDismiss to handle menu closing
+        assert "useDismiss" in source_code, (
+            "SearchBar should use useDismiss hook for menu dismissal"
+        )
+
+        # Verify that useDismiss is called with the appropriate refs
+        assert "selectorRef" in source_code, (
+            "SearchBar should track selectorRef for dismissal"
+        )
+        assert "controlsPanelRef" in source_code, (
+            "SearchBar should track controlsPanelRef for dismissal"
+        )