Hi,

 

I just test set

 

Editor1.Text="<h1>hello</h1>asdfkf<br/>dfkfjasd<br/>";

 

and open the page, switch to HTML, not able to reproduce your issue.

 

I select all test , and click the color button , I get such result :

 

<h1><span style="color: red">hello</span></h1>
<span style="color: red">asdfkf</span><br />
<span style="color: red">dfkfjasd</span><br />

 

I hope you can provide more information , so we can find the reason and fix it .

Regards,

Terry