TRichView.com

I want to insert a line in RichViewEdit.if I use the codes:
RichViewEdit1->InsertBreak(5, rvbsLine,clRed);
How can I control the length of the line?

I also want to control the range when I write in RichViewEdit.For example,
I don't want to use the 3cm from the left.But when I use RichEdit I can use the codes below :

TRect MyRect;
SendMessage(this->RichEdit1->Handle,EM_GETRECT,0,Longint(&MyRect));
MyRect.left = 120 ;
MyRect.Top = 20 ;
MyRect.right = MyRect.Bottom - 20;
SendMessage(this->RichEdit1->Handle,EM_SETRECT,0,Longint(&MyRect));

What is the reason?

Sorry, in the current version length of horizontal lines cannot be customized.

As for the second question, such functionality is not supported.
You can define LeftMargin, TopMargin, RightMargin, BottomMargin (properties of TRichView), but margins are scrolled with document.