Drop-down widget problem on save

Hi all

I have a widget that shows the featured image of the post. One of the options is to let the user pick the size of the thumbnail to appear. I’m using this,

<p><label for="<?php echo $this->get_field_id('size'); ?>"><?php _e('Image Size:'); ?></label><select class="widefat" id="<?php echo $this->get_field_id('size'); ?>" name="<?php echo $this->get_field_name('size'); ?>" />
    <?php $image_sizes=get_intermediate_image_sizes();
			foreach($image_sizes as $image_size) {
				echo '<option value="'.$image_size.'"';
					if($image_size==$size) echo ' selected="selected"';
				echo '>'.ucfirst($image_size).'</option>';
			} ?>
		</select></p>

as part of the form function in the class. It works great except that once the save button is pressed, the select has no options.

The result is saved as if I return to the widget page it shows correctly.

The must be some issue with the results returned from get_intermediate_image_sizes(), but for the life of me I don’t know what that is.

Any help appreciated!