I am having an issue adding a sub page to the home page, i'm running SS 3.0.1 and have tried this on 2 installs.

Can't add sub page to home page, when selecting the parent page in the tree-dropdown, it just jumps back to '(choose)'

Procedure to re-create error:
1. In the CMS, click the 'Pages' menu.
2. Click add page.
3. Select 'Under another page' option.
4. Then in the tree dropdown select the first item.
5. Notice the '(choose)' place holder still remains.

I think I have tracked it down to the file
/framework/javascript/TreeDropdownField.js Line 164
where the comment says '// Value is already selected, unselect it (for lack of a better UI to do this)'

When I click the item in the list it seems to be getting overridden with null. I'm not sure why.

Any clues?