Thanks for helping Adam.
Your example does not use the javascript API methods setHTML() and getHTML() on the editor. That is where the problem is for me. If the control is loaded invisible in Firefox, Chrome and Safari, the API is only initialized whenever the control becomes visible, which is too late to directly use the API methods and fill the editor...
I guess that maybe the following script tag with the "Loader" script is just not executed when the script tag is inside an invisible container in those browsers, or maybe the specific loader scripts for those browsers have slight changes that cause this problem...
- <script src="/CuteSoft_Client/CuteEditor/Load.ashx?type=scripts&file=(IE|Gecko|Safari)_Loader"></script>
I do seem to notice that hitting the "Show" button the first time in IE does instantly show the whole editor (with all toolbars preloaded in the background), while in other browsers the toolbars are still being loaded when the control becomes visual the first time.