Wrap the modal in a new stacking context

in the monolith, there were pages where tooltip triggers were showing through the modal backdrop

src/Nri/Ui/Modal/V7.elm

@@ -7,12 +7,11 @@ module Nri.Ui.Modal.V7 exposing
     , closeButton
     )
 
-{-| Changes from V5:
+{-| Changes from V6:
 
-  - Removes button helpers, now that we can use Nri.Ui.Button.V9 directly
-
-These changes have required major API changes. Be sure to wire up subscriptions!
+  - Modal starts a new stacking context, to prevent non-normal-flow elements from showing through the backdrop
 
+```
     import Html.Styled exposing (..)
     import Nri.Ui.Button.V9 as Button
     import Nri.Ui.Modal.V7 as Modal
@@ -49,6 +48,7 @@ These changes have required major API changes. Be sure to wire up subscriptions!
 
     view init
     --> text ""  -- a closed modal
+```
 
 
 ## State and updates
@@ -202,6 +202,8 @@ view { overlayColor, titleColor } config model =
         }
         model
         |> fromUnstyled
+        |> List.singleton
+        |> div [ css [ Css.position Css.relative, Css.zIndex (Css.int 1) ] ]
 
 
 toOverlayColor : Css.Color -> String

styleguide-app/Examples/Modal.elm

@@ -15,7 +15,7 @@ import ModuleExample exposing (Category(..), ModuleExample)
 import Nri.Ui.Button.V9 as Button
 import Nri.Ui.Checkbox.V5 as Checkbox
 import Nri.Ui.Colors.V1 as Colors
-import Nri.Ui.Modal.V6 as Modal
+import Nri.Ui.Modal.V7 as Modal
 
 
 {-| -}
@@ -46,7 +46,7 @@ init =
 {-| -}
 example : (Msg -> msg) -> State -> ModuleExample msg
 example parentMessage state =
-    { name = "Nri.Ui.Modal.V6"
+    { name = "Nri.Ui.Modal.V7"
     , category = Modals
     , content =
         [ Button.button "Launch Info Modal"