Fix up some issues with z-order manipulation.

glue_plotly/viewers/histogram/dotplot_layer_artist.py

@@ -40,6 +40,7 @@ def __init__(self, view, viewer_state, layer_state=None, layer=None):
 
         self._viewer_state.add_global_callback(self._update_dotplot)
         self.state.add_global_callback(self._update_dotplot)
+        self.state.add_callback("zorder", self._update_zorder)
 
     def _get_dots(self):
         return self.view.figure.select_traces(dict(meta=self._dots_id))
@@ -126,11 +127,12 @@ def _update_data(self):
         self._dots_id = dots[0].meta if dots else None
         self.view.figure.add_traces(dots)
 
-    def _update_zorder(self):
+    def _update_zorder(self, *args):
+        current_traces = self.view.figure.data
         traces = [self.view.selection_layer]
         for layer in self.view.layers:
             traces += list(layer.traces())
-        self.view.figure.data = traces
+        self.view.figure.data = traces + [t for t in current_traces if t not in traces]
 
     def _update_dotplot(self, force=False, **kwargs):
         if (self._viewer_state.hist_x_min is None or
@@ -156,9 +158,6 @@ def _update_dotplot(self, force=False, **kwargs):
         if force or len(changed & VISUAL_PROPERTIES) > 0:
             self._update_visual_attributes(changed, force=force)
 
-        if force or "zorder" in changed:
-            self._update_zorder()
-
     def update(self):
         self.state.reset_cache()
         self._update_dotplot(force=True)

glue_plotly/viewers/histogram/layer_artist.py

@@ -35,6 +35,7 @@ def __init__(self, view, viewer_state, layer_state=None, layer=None):
 
         self._viewer_state.add_global_callback(self._update_histogram)
         self.state.add_global_callback(self._update_histogram)
+        self.state.add_callback("zorder", self._update_zorder)
 
     def _get_bars(self):
         return self.view.figure.select_traces(dict(meta=self._bars_id))
@@ -122,11 +123,12 @@ def _update_data(self):
         self._bars_id = bars[0].meta if bars else None
         self.view.figure.add_traces(bars)
 
-    def _update_zorder(self):
+    def _update_zorder(self, *args):
+        current_traces = self.view.figure.data
         traces = [self.view.selection_layer]
         for layer in self.view.layers:
             traces += list(layer.traces())
-        self.view.figure.data = traces
+        self.view.figure.data = traces + [t for t in current_traces if t not in traces]
 
     def _update_histogram(self, force=False, **kwargs):
         if (self._viewer_state.hist_x_min is None or
@@ -152,9 +154,6 @@ def _update_histogram(self, force=False, **kwargs):
         if force or len(changed & VISUAL_PROPERTIES) > 0:
             self._update_visual_attributes(changed, force=force)
 
-        if force or "zorder" in changed:
-            self._update_zorder()
-
     def update(self):
         self.state.reset_cache()
         self._update_histogram(force=True)

glue_plotly/viewers/scatter/layer_artist.py

@@ -69,6 +69,7 @@ def __init__(self, view, viewer_state, layer_state=None, layer=None):
 
         self._viewer_state.add_global_callback(self._update_display)
         self.state.add_global_callback(self._update_display)
+        self.state.add_callback("zorder", self._update_zorder)
 
         self.view = view
 
@@ -166,14 +167,12 @@ def _update_display(self, force=False, **kwargs):
         if force or len(changed & LINE_PROPERTIES) > 0:
             self._update_lines(changed, force=force)
 
-        if force or "zorder" in changed:
-            self._update_zorder()
-
-    def _update_zorder(self):
+    def _update_zorder(self, *args):
+        current_traces = self.view.figure.data
         traces = [self.view.selection_layer]
         for layer in self.view.layers:
             traces += list(layer.traces())
-        self.view.figure.data = traces
+        self.view.figure.data = traces + [t for t in current_traces if t not in traces]
 
     def _update_lines(self, changed, force=False):
         scatter = self._get_scatter()