block_titlelink.module

<?php

// Variable Table Prefex
define('BLOCK_TITLELINK_VARIABLE_PREFIX','block_titlelink_');

function block_titlelink_form_alter(&$form, &$form_state, $form_id) {
  if ($form_id == 'block_admin_configure') {
    $block->module = $form['module']['#value'];
    $block->delta = $form['delta']['#value'];
    $link = _block_titlelink_get_link($block);
    //Assign weight to block title so it appears above link
    if(!isset($form['block_settings']['#weight'])) {
      $form['block_settings']['#weight'] = -1;
    }    
    $form['block_titlelink'] = array(
      '#type' => 'fieldset',
      '#title' => t('Block Title Link settings'),
      '#collapsible' => TRUE,
      '#weight' => 0,
    );
    $form['block_titlelink']['title_path'] = array(
      '#type' => 'textfield',
      '#title' => t('Title Path'),
      '#default_value' => $link,
      '#description' => t('URL for Block Title to link to.'),
    );
    
   $form['#validate'][] = 'block_titlelink_validate';
  }
}

/**
 * Implementation of hook_validation()
**/
function block_titlelink_validate($form, &$form_state) {
  if ($form_state['values']['form_id'] == 'block_admin_configure') {
    if (isset($form_state['values']['title_path']) && user_access('administer blocks')) {
      $module = arg(4);
      $delta = arg(5);
      //TODO: Validate Link based on URL and PATH
      $link = $form_state['values']['title_path'];
      //Save Form Link
      if($module && $delta && $link) {
        $name = $module . '_' . $delta;
        //Delete link if empty
        if(strlen($link) == 0) {
          _block_titlelink_delete_link($name);
        }
        else {
          _block_titlelink_save_link($name,$link);
        }
      }
    }
  }
  block_admin_configure_validate($form, $form_state);
}

/**
 * TODO: Function to pre-process block to add title link
**/
function block_titlelink_preprocess_block(&$vars, $hook) {  
  if($hook == 'block') {
    $var_name = $vars['block']->module . '_' . $vars['block']->delta;
    $vars['block']->title_link = _block_titlelink_get_link($vars['block']);
  }
}

/**
 * Function to return a title link of a block
 * @param array $block - Block to search by
 * @return string Title Link
**/
function _block_titlelink_get_link($block) {
  if(!isset($block->module) && !isset($block->delta)) {
    return FALSE;
  }
  $varname = BLOCK_TITLELINK_VARIABLE_PREFIX . $block->module . '_' . $block->delta;
  return variable_get($varname,NULL);
}

/**
 * Function to save a title link block
 * @param string $name - Variable name (module . '_' . delta)
 * @param string $value - A valid drupal path or URL
 * @return void
**/
function _block_titlelink_save_link($name,$value) {
  $varname = BLOCK_TITLELINK_VARIABLE_PREFIX . $name;
  variable_set($varname, $value);
}

/** 
 * Function to delete a link variable
 * @param string $name 
**/
function _block_titlelink_delete_link($name) {
  $varname = BLOCK_TITLELINK_VARIABLE_PREFIX . $name;
  variable_del($varname);
}