Martyn,

 

Open Providers\HtmlEditorProviders\CEHtmlEditorProvider\CEHtmlEditorProvider.vb and change:

 

 

           Set(ByVal Value As System.Web.UI.WebControls.Unit)
                '    If _UseDNNDefaultWidth = True Then
                cntlCE.Width = Value
                '   End If
            End Set

 

to:

 

           Set(ByVal Value As System.Web.UI.WebControls.Unit)
                If _UseDNNDefaultWidth = True Then
                   cntlCE.Width = Value
                End If
            End Set

 

Then recompile the provider project.

 

or download this DLL: