The Find and Replace dialog could be enabled in HTML mode only in IE and this is supported only by RadEditor for ASP.NET AJAX. You can test the AJAX editor in this example: Default settings
If the classic editor (RadEditor.dll) is used in RedDot there is not way to enable this tool in HTML mode, but you can use the built-in Find feature of the browser by hitting the Ctrl+F shortcut key combination.
You can see how to hide the preview mode of RadEditor for ASP.NET AJAX in this article Edit Modes
To hide the Preview mode of RadEditor Classic just set the ShowPreviewMode
property to "false
All the best,
the Telerik team
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