Okay, I think this will satisfy your needs. Backspace and delete still work in their standard left-to-right fashion, but otherwise I don't think there will be any problems. 
#!/usr/bin/perl
# urdu.pl, written by Mike Foster
# feel free to reuse, modify, redistribute,
# bend, fold, staple, or mutilate.

use strict;
use warnings;
use Tk;

my $lastlength=1;
my $lastdepth=1;
my $mw = MainWindow->new(
    -background=>"darkviolet"
    );
$mw->title('Right-to-left text entry');

my $t1 = $mw->Text(
       -background=>"navy",
       -foreground=>"white",
       -height=>35,
       -width=>80,
       -wrap=>"word",
       -selectbackground=>"blueviolet"
       )->pack;
$t1->bind("<Key>" => \&rtl);

sub rtl {
    #gets end position
    my $depth = $t1->index('end');
    #reduces to line
    $depth =~ s/\..*$//;
    #converts back to an integer
    $depth--;
    if ($lastdepth < $depth) {
        $t1->SetCursor('insert - 1 lines lineend');
    }
    #remember where we were
    $lastdepth = $depth;
    
    #gets end of current line
    my $length = $t1->index('insert lineend');
    #reduces to character number
    $length =~ s/^.*\.//;
    #converts back to integer
    $length++;
    if ($lastlength < $length) {
        $t1->SetCursor('insert - 1 chars');
    }
    #remember where we were
    $lastlength = $length;
}

MainLoop;

[download]

--
Linux, sci-fi, and Nat Torkington, all at Penguicon 3.0

In reply to Re: right to left Tk text widget by wolfger
in thread right to left Tk text widget by davidj

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.