Count context menu clicks when considering the click outside handler

packages/bbui/src/Actions/click_outside.js

@@ -29,6 +29,7 @@ const handleClick = event => {
   })
 }
 document.documentElement.addEventListener("click", handleClick, true)
+document.documentElement.addEventListener("contextmenu", handleClick, true)
 
 /**
  * Adds or updates a click handler

packages/frontend-core/src/components/sheet/cells/HeaderCell.svelte

@@ -47,7 +47,7 @@
 
   const onContextMenu = e => {
     e.preventDefault()
-    open = true
+    open = !open
   }
 
   const sortAscending = () => {