Cannot Set Design Mode on iFrame

When iFrame is in htc file

[Red_Eye]

I have created and html editor in a htc file which works fine with and editable div tag.
Now to add more features I am trying to use an iFrame with designMode="On". This works if it is in a html file but as soon as I put it in an htc file I cannot set the design mode to on.
I have search the web but can find no refernace to not being allowed this feature in a html Component. Any ideas?

[tedster]

Sorry Red_Eye, I'm having no better luck than you in researching this. I don't play around with htc very much, so maybe someone else has an insight to help out.

[Bernard Marx]

Maybe:

<PUBLIC:DEFAULTS
  canHaveHTML = "bCanHaveHTML"
  [blue]contentEditable[/blue] = "bEditable"
  style = "sStyle"
  tabStop = "bIsTabStop"
  viewInheritStyle = "bInheritsStyle"
  viewLinkContent = "bViewLinkContent"
  viewMasterTab = "bViewMasterTab"
/>

[msdn.microsoft.com...]