Deleting categories that are usesd or have children - warnin

I had a couple of categories like

Photos
 - 2011
 - 2012
 - 2013

Wanted to delete 2011 and 2012 and checked the checkbox. Did not see that the checkbox of Photos was also checked .

I figured out how it was checked. When I wanted to expand Photos I clicked about two pixel to far left of the arrow for expanding. This resulting in selecting the checkbox of Photo. Now when I expanded it the checkbox styed checked. 

Checked the two I wanted to delete and clicked delete. Resulting in deleting every categorie even the once I had noch ckecked (2013) because Photos was checked.

Hard to explain screencast will explain better. www.marktold.com/screencast/sf_delete_categories.swf

Of course I had many more categories under Photos. So this stupied mistake made me a lot of work. 

So here is what I think should happen

a) only when you click the checkbox it should be checked not like www.marktold.com/screencast/sf_selecting.swf

b) if you have a parent categorie checked and want to delete it it should warn you that it will delete ALL children and grandchildren and grand grand children. Yes I had quite a hiarchiy

c) maybe it should only be possible to delete categories that are not used

d) maybe it should only be possible to delete parent categories as long as there are childern


I know the user has to be carefull what they delete. But let me tell you from my own experiance now. Sh.. happens. 

Markus