How to customize the "ModalWindow" size when I extend Vsphere Client with my own plugin

I want to extend InventorayView and popup my own page in a modal window, is there any way to customize the modal window size? I didn't find the related solution in “Customizing the vSphere Client” pdf, Is there some related tags or attributes in extension configuration xml can be used to achieve it，or any other solutions？

<extension parent="InventoryView.Template">

<title locale="en">Custom Template</title>

<url display="modalwindow">http://fqdn/path/to/plugin/component/a.html</url>

</extension>

Thank you.