No, it doesn't work. Same deal here. One of the handful of reasons I ditched 3.0.0 for my current project. The widgets tab, although present and has all the items listed -- links are all inactive, as you described. Looks like there is plainly no Edit_Form at all.
Have not had a chance to fully test it but the interface appears to be working in undfinedoffset's branch. He has a pending pull request.
Yes I've had exactly the same problem with blog widgets showing up but being unable to interact with them at all. Did anyone manage to get this working at all?
Also, in case anyone makes the same mistake I made which left me scratching my head for a while: make sure you install the widget module in the root in a folder called "widget", NOT "widgets". Note: the above statement turns out to be baloney: seems to work the same whether the directory is called "widget" or "widgets".
One other thing I've noticed: after implementing widgets in Page.php I get the same unresponsive list of widgets in the widgets tab for Page pagetype, but when viewing the widgets tab on BlogHolder pagetype the list of widgets appears twice. Not sure if this is another bug or if I'm missing something (haven't had the time to fully investigate this yet).
Your widgets display twice because you implemented the WidgetAreaEditor in page.php which is inherited by blog.php. To solve this remove the following two lines from page.php and add them to a newly created page type e.g. PageWithWidgets.php.
"NAMEOFWIDGETAREA" => "WidgetArea"
$fields->addFieldToTab("Root.Widgets", new WidgetAreaEditor("NAMEOFWIDGETAREA"));
You will also need to copy page.ss and rename it respectively e.g. PageWithWidgets.ss. Copying page.ss will give you the same layout you had before.
Hope this helps.
PS: I have the same error as you guys regarding the widgets being inactive in SS3. Had anyone solved this? I hope so because this is driving me crazy!
EDIT: Alternatively, to avoid creating a new page type, you could simply comment out the following line(30) in BlogHolder.php and remove the DB entry by running a http://www.mysite.com/db/build.
// $fields->addFieldToTab("Root.Content.Widgets", new WidgetAreaEditor("SideBar")); COMMENT OUT
I found this alternative solution on the silverstripe widgets page https://github.com/silverstripe/silverstripe-widgets