import bpy
from bpy.props import IntProperty

class TEST(bpy.types.Operator):

	bl_idname = "test.modal"
	bl_label = "test invoke props + modal"

	nb = IntProperty(name="int prop")

	def invoke(self, context, event):
		return context.window_manager.invoke_props_dialog(self)
		
	def execute(self, context):
		context.window_manager.modal_handler_add(self)
		return {'RUNNING_MODAL'}

	def modal(self, context, event):

		if event.type in {'ESC'}:
			return {'CANCELLED'}

		return {'RUNNING_MODAL'}

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


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

if __name__ == "__main__":
	register()