nig_rishat_n.py

bl_info = { 
    "name": "My First Addon",
    "category": "3D View"
}


import bpy


class MyOperator(bpy.types.Operator):
    bl_idname = "nig_rishat.append"
    bl_label = "Append Door"

    def execute(self, context):
        bpy.ops.wm.append(directory="/D:/Project_Blender/windows/w1.blend/Object/", filepath="w1.blend", filename="Cube.000")
        return {'FINISHED'}


class MyPanel(bpy.types.Panel):
    bl_label = "My Menu"
    bl_space_type = 'VIEW_3D'
    bl_region_type = 'TOOLS'

    def draw(self, context):
        layout = self.layout
        
        layout.label(text="Windows")
        layout.operator("mesh.primitive_plane_add")
        
        layout.label(text="Doors")
        layout.operator("nig_rishat.append")


def register():
    bpy.utils.register_class(MyOperator)
    bpy.utils.register_class(MyPanel)


def unregister():
    bpy.utils.unregister_class(MyOperator)
    bpy.utils.unregister_class(MyPanel)


if __name__ == "__main__":
    register()