Set `brokers: list[st]` from mods when not provided..

piker/data/feed.py

@@ -1450,6 +1450,7 @@ class Feed(Struct):
 
         if brokers is None:
             mods = self.mods
+            brokers = list(self.mods)
         else:
             mods = {name: self.mods[name] for name in brokers}
 

piker/ui/_overlay.py

@@ -304,7 +304,7 @@ class PlotItemOverlay:
         # NOTE: required for scene layering/relaying; this guarantees
         # the "root" plot receives priority for interaction
         # events/signals.
-        root_plotitem.vb.setZValue(1000)
+        root_plotitem.vb.setZValue(10)
 
         self.overlays: list[PlotItem] = []
         self.layout = ComposedGridLayout(root_plotitem)
@@ -494,6 +494,8 @@ class PlotItemOverlay:
         root.vb.setFocus()
         assert root.vb.focusWidget()
 
+        vb.setZValue(100)
+
     def get_axis(
         self,
         plot: PlotItem,