Let view supps give data instead of actual xref button

tailbone/templates/master/view.mako

@@ -57,16 +57,24 @@
       % if use_buefy:
           <nav class="panel">
             <p class="panel-heading">Cross-Reference</p>
-            <div class="panel-block">
+            <div class="panel-block buttons">
+              <div style="display: flex; flex-direction: column;">
+                % for button in xref_buttons:
+                    ${button}
+                % endfor
                 % for link in xref_links:
                     ${link}
                 % endfor
               </div>
+            </div>
           </nav>
       % else:
           <div class="object-helper">
             <h3>Cross-Reference</h3>
             <div class="object-helper-content">
+              % for button in xref_buttons:
+                  ${button}
+              % endfor
               % for link in xref_links:
                   ${link}
               % endfor

tailbone/views/master.py

@@ -2510,13 +2510,40 @@ class MasterView(View):
     def get_xref_buttons(self, obj):
         buttons = []
         for supp in self.iter_view_supplements():
-            buttons.extend(supp.get_xref_buttons(obj))
+            buttons.extend(supp.get_xref_buttons(obj) or [])
+        buttons = self.normalize_xref_buttons(buttons)
         return buttons
 
+    def normalize_xref_buttons(self, buttons):
+        normal = []
+        for button in buttons:
+
+            # build a button if only given the data
+            if isinstance(button, dict):
+                button = self.make_xref_button(**button)
+
+            normal.append(button)
+        return normal
+
+    def make_xref_button(self, **kwargs):
+
+        # nb. unfortunately HTML.tag() calls its first arg 'tag' and
+        # so we can't pass a kwarg with that name...so instead we
+        # patch that into place manually
+        button = HTML.tag('b-button', type='is-primary',
+                          href=kwargs['url'], target='_blank',
+                          icon_pack='fas', icon_left='external-link-alt',
+                          c=kwargs['text'])
+        button = six.text_type(button)
+        button = button.replace('target="_blank"',
+                                'target="_blank" tag="a"')
+        button = HTML.literal(button)
+        return button
+
     def get_xref_links(self, obj):
         links = []
         for supp in self.iter_view_supplements():
-            links.extend(supp.get_xref_links(obj))
+            links.extend(supp.get_xref_links(obj) or [])
         return links
 
     def template_kwargs_edit(self, **kwargs):
@@ -5079,6 +5106,7 @@ class ViewSupplement(object):
         self.master = master
         self.request = master.request
         self.model = master.model
+        self.rattail_config = master.rattail_config
 
     def get_grid_query(self, query):
         """