Summary:

ModalFormData.icon() has the argument "iconPath: string" and ActionFomrData.button() has same one.
From above, I consider these usages to be the same.

Thus, I expected that setting the same arguments to these would yield the same results, but that failed.

The result is that the icon is displayed only on ActionForm and not on ModalForm.

Step to reproduce:

1. Define an ActionForm and add a button with icon to it.
2. Define a ModalForm and add an icon and some input to it. The iconPath must be same as ActionForm.
3. Start game and show defined forms in any way you wish..

Observed results:

The specified icon is displayed on ActionForm, but nothing on ModalForm.

Expected results:

The specified icon is displayed on both of ActionForm and ModalForm.