PopupTemplate

import bpy



class ADDONNAME_PT_TemplatePanel(bpy.types.Panel):
    bl_label = "Name of the Panel"
    bl_idname = "ADDONNAME_PT_TemplatePanel"
    bl_space_type = "VIEW_3D"
    bl_region_type = 'UI'
    bl_category = "Template Tab"

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

        layout.operator("wm.template_operator")






class ADDONAME_OT_TemplateOperator(bpy.types.Operator):
    bl_label = "Template Operator"
    bl_idname = "wm.template_operator"





    def invoke(self, context, event):
        wm = context.window_manager
        return wm.invoke_props_dialog(self)


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


    def execute(self, context):

        return {'FINISHED'}








classes = [ADDONNAME_PT_TemplatePanel, ADDONAME_OT_TemplateOperator]



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()