I'm using SS 2.4.5 with Blog module 0.4.1.
The variables $default_parent and $can_be_root seem to not have any effect on the blog entries in the site tree. Here's the behavior I'm seeing:
A user has a Blog entry open in the CMS and clicks the 'Create' button. This moves the "focus" (Bluish-purple bar in site tree) to the root of the site. Then when a new BlogEntry is created it is at the bottom of the site tree, which shouldn't be possible since $can_be_root is false, and I believe $default_parent should refocus the blue bar when "Blog Entry" is selected. If the create button is already selected and the pagetype dropdown is visible then a new BlogEntry will become a child of the current blog entry I'm assuming $default_parent is supposed to take care of this too?
Also I noticed that $default_parent is set to "BlogHolder". In the [url=http://doc.silverstripe.org/sapphire/en/reference/sitetree]documentation of SiteTree[/url] it says that $default_parent should be set to the URLSegment rather than the class name. So something is either wrong in the module or the documentation.
It seems like a rather trivial practice to click on the BlogHolder before creating the page (or clicking create, then BlogHolder, then create the page), but if the users of my site are having trouble with this, then I figured others' might too. Further, if you do make the mistake, it cannot be corrected by dragging and dropping the BlogEntry back under the BlogHolder. It will let you drag and drop, but you will get "error saving order" until you go to the Behavior Tab and change the Parent page to the BlogHolder.
Is anyone else seeing this problem? I'll open a ticket if I'm not the only one with the problem.