Nav: Fixed an issue with NavFlattened window flag where widgets not entirely fitting in child window (often selectable because of their extruded bits) would be not considered to navigate toward the child window. (#787)

This creates a little bit of tension because g.NavDisableHighlight tends to makes the reference point not always visible.
Amend c665c15a7d

imgui.cpp

@@ -7761,7 +7761,7 @@ static bool NavScoreItem(ImGuiNavMoveResult* result, ImRect cand)
     if (window->ParentWindow == g.NavWindow)
     {
         IM_ASSERT((window->Flags | g.NavWindow->Flags) & ImGuiWindowFlags_NavFlattened);
-        if (!window->ClipRect.Contains(cand))
+        if (!window->ClipRect.Overlaps(cand))
             return false;
         cand.ClipWithFull(window->ClipRect); // This allows the scored item to not overlap other candidates in the parent window
     }