blender-package-manager-addon/pkg_ui.py

import bpy
from . import pkg_ops

class USERPREF_PT_packages(bpy.types.Panel):
    bl_label = "Package Management"
    bl_space_type = 'USER_PREFERENCES'
    bl_region_type = 'WINDOW'
    bl_options = {'HIDE_HEADER'}

    @classmethod
    def poll(cls, context):
        userpref = context.user_preferences
        return (userpref.active_section == 'PACKAGES')

    def draw(self, context):
        wm = context.window_manager
        # see comment in __init__.py
        pm_settings = wm.package_manager_settings
        layout = self.layout

        row = layout.row()
        row.prop(pm_settings, "url")
        row.operator(pkg_ops.PACKAGE_OT_fetch.bl_idname, text="Fetch")

        row = layout.row()
        # just a demonstration
        row.label(text="Last response: %s" % pkg_ops.PACKAGE_OT_fetch.last_response)

def register():
    bpy.utils.register_class(USERPREF_PT_packages)

def unregister():
    bpy.utils.unregister_class(USERPREF_PT_packages)