Fix T82453: Icon Viewer: No button on console header

Caused by rB4b20eebb85cc.

Apparently the Addon misused the API though and it is not allowed to
register multiple headers, instead, we need to append to the existing
one.

Maniphest Tasks: T82453

Differential Revision: https://developer.blender.org/D9579

development_icon_get.py

@@ -296,17 +296,6 @@ class IV_PT_icons(bpy.types.Panel):
         return prefs().show_panel
 
 
-class IV_HT_icons(bpy.types.Header):
-    bl_space_type = 'CONSOLE'
-
-    def draw(self, context):
-        if not prefs().show_header:
-            return
-        layout = self.layout
-        layout.separator()
-        layout.operator(IV_OT_icons_show.bl_idname)
-
-
 class IV_OT_panel_menu_call(bpy.types.Operator):
     bl_idname = "iv.panel_menu_call"
     bl_label = ""
@@ -487,10 +476,13 @@ class IV_OT_icons_show(bpy.types.Operator):
         return context.window_manager.invoke_props_dialog(
             self, width=self.width)
 
+def draw_console_header(self, context):
+    if not prefs().show_header:
+        return
+    self.layout.operator(IV_OT_icons_show.bl_idname)
 
 classes = (
     IV_PT_icons,
-    IV_HT_icons,
     IV_OT_panel_menu_call,
     IV_OT_icon_select,
     IV_OT_icons_show,
@@ -505,10 +497,14 @@ def register():
     for cls in classes:
         bpy.utils.register_class(cls)
 
+    bpy.types.CONSOLE_HT_header.append(draw_console_header)
+
 
 def unregister():
     if bpy.app.background:
         return
 
+    bpy.types.CONSOLE_HT_header.remove(draw_console_header)
+
     for cls in classes:
         bpy.utils.unregister_class(cls)