CB-5092 Top navigation bar is not visible (#2616)

* CB-5092 fix: combobox opens on small screens without eating off a bottom space of the window

* CB-5092 does arrow click in separate function

* CB-5092 fix: selectors and nodes context menu do not break layout for small screens

---------

Co-authored-by: Daria Marutkina <125263541+dariamarutkina@users.noreply.github.com>

webapp/packages/core-blocks/src/FormControls/Combobox.tsx

@@ -106,6 +106,7 @@ export const Combobox: ComboboxType = observer(function Combobox({
     placement: 'bottom-end',
     currentId: null,
     gutter: 4,
+    unstable_fixed: true,
   });
 
   if (readOnly) {

webapp/packages/core-blocks/src/Menu/Menu.tsx

@@ -70,6 +70,7 @@ export const Menu = observer<IMenuProps, HTMLButtonElement>(
       placement,
       visible,
       rtl,
+      unstable_fixed: true,
     });
     const styles = useS(style);