I know this issue well.
All non-IE browsers will have problems when you dynamically show the editor in the page.
It’s a common issue that happens to all editors. You can search this topic: designMode doesn't work for display:none iframe
The best method is loading the editor first in the page then hide it.
Another work-around is detecting non-IE browsers and adding the loading script in the page:
In the new version of editor, we implement a very new method to achieve wysiwyg editing.
This issue is resolved. But due to we have to rewrite all code in this new version and add many new features, there are still some works not finished.
Here is the screenshot of 8.0.
We can publish a testing version in support forums soon.
Hope this information helps.
asp.net Chat http://cutesoft.net/ASP.NET+Chat/default.aspx
Web Messenger: http://cutesoft.net/Web-Messenger/default.aspx
asp.net wysiwyg editor: http://cutesoft.net/ASP.NET+WYSIWYG+Editor/default.aspx
asp wysiwyg html editor: http://cutesoft.net/ASP
asp.net Image Gallery: http://cutesoft.net/ASP.NET+Image+Gallery/default.aspx
Live Support: http://cutesoft.net/live-support/default.aspx