FF: Fields in iframe dialog are empty when context menu is opened by right clicking on a resize handle

[James Cunningham]

Steps to reproduce the defect:

1. Open the Ajax sample in Firefox.

2. Open the iframe dialog.

3. Enter the following URL ​http://www.youtube.com/embed/rWTY8xtiZjc & click OK.

4. Click on the iframe placeholder to select the iframe.

5. Right click on one of the iframe placeholder resize handles (when the resize arrows are black) to display the context menu.

6. Choose iframe from the context menu to display the iframe dialog.

Result: The iframe dialog is displayed but all of the text fields in the dialog are empty.

[Garry Yao]

Right click on one of the iframe placeholder resize handles (when the resize arrows are black) to display the context menu.

AFAIK this's pretty trick and e.g. on FF4 I simply cannot make context menu in this way, so we should not rely on that for opening menu.