What is meant by "The code added above is:" followed by "<input button..." ? I can reconstruct the other patches but I don't understand what's meant here.

Sorry, that was an awkward way to show the changes, but I couldn't highlight a section of text in the code block to show what I added. The "<input button..." code was the code ADDED to the block of code above it. Look through it and you will see it hiding in there somewhere.

Here is another way of showing where to add the code. In my editor it starts at line 203:

 
<td colspan="2"><input type="submit" name="save_entry" value="{#message_submit_button#}" title="{#message_submit_title#}" tabindex="8" onclick="return is_postingform_complete('{$smarty.config.error_no_name|escape:"url"}','{$smarty.config.error_no_subject|escape:"url"}','{if $settings.empty_postings_possible==0}{$smarty.config.error_no_text|escape:"url"}{/if}'{if $terms_of_use_agreement},'{$smarty.config.terms_of_use_agree_error_posting|escape:"url"}'{/if})" />&nbsp;<input type="submit" name="preview" value="{#message_preview_button#}" title="{#message_preview_title#}" tabindex="9" onclick="return is_postingform_complete('{$smarty.config.error_no_name|escape:"url"}','{$smarty.config.error_no_subject|escape:"url"}','{if $settings.empty_postings_possible==0}{$smarty.config.error_no_text|escape:"url"}{/if}'{if $terms_of_use_agreement},'{$smarty.config.terms_of_use_agree_error_posting|escape:"url"}'{/if})" />&nbsp;

Add this right after the above code:

<input type="button" value="Check Spelling" onClick="openSpellChecker();"/>&nbsp;

I visited the "Try it here:" link but it doesn't work, the message "Fehler auf der Seite" appears in the status line.

I don't know German, but I think that means "Error on site." Mmmm...maybe my shared server was having problems? It's working now for me. Please let me know if it still doesn't work.

http://appbbs.com/mlf

Also: What mlf version are the positions for the changes (line numbers) related to?

I'm using the latest version.

I *think* those were the only mlf-specific changes needed to make it work; it's been a while since I installed it. If it doesn't work, let me know. I may be forgetting something. (I was dropped on my head as a baby.)