Since the RichTexrSelection is now setable for the RichTextEditor control, if feels like necessary to provide the support for add/change specified content at specified position.
We can change the content programmatically in 2 conditions:
1. Insert plain text / html code at the cursor point, while there is nothing selected.
2.Replace the currently selected content with new plain text / html code while selection exists.
Just for reference, an Api as below would be ideal:
For example, if I want to insert some plain text at the beginning of the document just after the rich text file loaded, I can easly achieve by this:
richTextEditor.Selection = new RichTextSelection(0,0);
Hope the suggeation could be accepted.