bpo-36176: Fix IDLE autocomplete & calltip popup colors. (#12262)

Prevent conflicts with Linux dark themes
(and slightly darken calltip background).
diff --git a/Lib/idlelib/NEWS.txt b/Lib/idlelib/NEWS.txt
index 58050f6..c771dd0 100644
--- a/Lib/idlelib/NEWS.txt
+++ b/Lib/idlelib/NEWS.txt
@@ -3,7 +3,11 @@
 ======================================
 
 
-bpl-36152: Remove colorizer.ColorDelegator.close_when_done and the
+bpo-36176: Fix IDLE autocomplete & calltip popup colors.
+Prevent conflicts with Linux dark themes
+(and slightly darken calltip background).
+
+bpo-36152: Remove colorizer.ColorDelegator.close_when_done and the
 corresponding argument of .close().  In IDLE, both have always been
 None or False since 2007.
 
diff --git a/Lib/idlelib/autocomplete_w.py b/Lib/idlelib/autocomplete_w.py
index 7994bc0..c249625 100644
--- a/Lib/idlelib/autocomplete_w.py
+++ b/Lib/idlelib/autocomplete_w.py
@@ -189,7 +189,7 @@
             pass
         self.scrollbar = scrollbar = Scrollbar(acw, orient=VERTICAL)
         self.listbox = listbox = Listbox(acw, yscrollcommand=scrollbar.set,
-                                         exportselection=False, bg="white")
+                                         exportselection=False)
         for item in self.completions:
             listbox.insert(END, item)
         self.origselforeground = listbox.cget("selectforeground")
diff --git a/Lib/idlelib/calltip_w.py b/Lib/idlelib/calltip_w.py
index 7553dfe..1e0404a 100644
--- a/Lib/idlelib/calltip_w.py
+++ b/Lib/idlelib/calltip_w.py
@@ -80,7 +80,8 @@
     def showcontents(self):
         """Create the call-tip widget."""
         self.label = Label(self.tipwindow, text=self.text, justify=LEFT,
-                           background="#ffffe0", relief=SOLID, borderwidth=1,
+                           background="#ffffd0", foreground="black",
+                           relief=SOLID, borderwidth=1,
                            font=self.anchor_widget['font'])
         self.label.pack()