I haven't used Prima and my Perl version is so ancient that I couldn't easily get that library running on my machine. I have constructed a Tk way of doing this as shown below.

In Tk there is a "Frame" widget which usually has invisible borders. Things inside of a Frame widget get grouped. In the example below, there is a text label on the left; all of them are stuffed into a Frame. And then within that Frame, they are right justified and anchored to the east. The Frame will expand to accommodate the longest label.

In Prima, I see that there is a FrameSet gizmo. This may get you similar function to a Tk Frame.

Run this and let us know how close it is to your requirements.

Added:
I did set one width manually, the input field width, I forget what the units are but you can play around with it. 

se warnings;
use strict;
use Tk;

my $mw = MainWindow->new();
$mw->configure(-title=> "Some Title");
$mw->minsize(qw(700 200));

my $mainDataFrame = $mw->Frame()->pack(-side=>'top', -fill=>'x');
my $labelFrame = $mainDataFrame->Frame->pack(-side=>'left');
my $dataEntryFrame = $mainDataFrame->Frame->pack(-side=>'left');
my $unitsFrame = $mainDataFrame->Frame->pack(-side=>'left');

my $refreshRate;
my $spectralRes;
my $showSpectrumHz;

my @tableConfig = ( ['Refresh rate:','60',\$refreshRate,'FPS'],
                    ["Spectral resolution",'10',\$spectralRes,'Hz'],
                    ["Show spectrum up to",'5000',\$showSpectrumHz,'Hz
+']);
               
for my $rowRef ( @tableConfig )
{
    $labelFrame->Label(-text => "$rowRef->[0]",
                       -anchor=>'e',
                       -justify => 'right')->pack(-side=>'top', -fill 
+=> 'x');
    
    my $dataRef = $rowRef->[2]; # put default value into textvariable
    $$dataRef   = $rowRef->[1];
    $dataEntryFrame->Entry(-width => 8,
                           -textvariable => $dataRef,
                           )->pack(-side =>'top', -fill => 'x');
   
    $unitsFrame->Label(-text => "$rowRef->[3]",
                       -anchor=>'w',
                       -justify => 'left')->pack(-side=>'top', -fill =
+> 'x');
}

MainLoop();

[download]

In reply to Re: Prima: How to get a "table" layout? by Marshall
in thread Prima: How to get a "table" layout? by haj

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.