import bpy





class ADDONNAME_PT_main_panel(bpy.types.Panel):
    bl_label = "Main Panel"
    bl_idname = "ADDONNAME_PT_main_panel"
    bl_space_type = 'VIEW_3D'
    bl_region_type = 'UI'
    bl_category = "New Tab"

    def draw(self, context):
        layout = self.layout

        obj = context.object

        row = layout.row()
        row.label(text="Hello world!", icon='WORLD_DATA')

        row = layout.row()
        row.label(text="Active object is: " + obj.name)
        row = layout.row()
        row.prop(obj, "name")

        row = layout.row()
        row.operator("addonname.myop_operator")






class ADDONNAME_OT_my_op(bpy.types.Operator):
    bl_label = "Operator"
    bl_idname = "addonname.myop_operator"



    def execute(self, context):
        return {'FINISHED'}










classes = [ADDONNAME_PT_main_panel, ADDONNAME_OT_my_op]



def register():
    for cls in classes:
        bpy.utils.register_class(cls)

def unregister():
    for cls in classes:
        bpy.utils.unregister_class(cls)



if __name__ == "__main__":
    register()