What about elgg_in_context ?

if(elgg_in_context('dashboard')) {

return false;

}

@RVR Where would that pice of code go????? Would it replace the one which I commment out to remove it from the whole site?

There's 2 ways:

1 - Add 'show_add_widgets' => false, in array for widget parameters on your 'dashboard' page

2 - Show your widget code with the existing arrays but set limit for showing add widgets button on dashboard like as:

if(elgg_in_context('dashboard')) {

  $params = array(
        'num_columns' => 3,
        'exact_match' => true,
        'show_add_widgets' => false,
    );

}

Add it in start.php of your theme

This just does not seam to want to work for me grr.

Find this file:

\views\default\page\layouts\widgets\add_button.php

Edit it to:

<?php
/**
 * Button area for showing the add widgets panel
 */
if(elgg_in_context('groups')||elgg_in_context('profile')){
    echo "<div class=\"elgg-widget-add-control\">";
    echo elgg_view('output/url', array(
        'href' => '#widgets-add-panel',
        'text' => elgg_echo('widgets:add'),
        'class' => 'elgg-button elgg-button-action',
        'rel' => 'toggle',
        'is_trusted' => true,
    ));
    echo "</div>";
}
?>

This is the way I have done. It works well, but I don't ensure that is the best way.