Linus Ekström writes in a comment to his own post here how to do it.

Just put this in the language file to override the default text:
<episerver>
<cms>
<widget>
<overlay>
<blockarea>
<emptyactions>
<template>You can drop content here</template>
</emptyactions>
</blockarea>
</overlay>
</widget>
</cms>
</episerver>

Thanks. However this will disable it for all content areas. I would like to be able to disable it per content area. Preferrably through an attribute on the declaration, along the lines of AllowedTypes...

Something like

[CultureSpecific]
[AllowedTypes(typeof(BannerBlock))]
[AddNewEnabled(false)]
public virtual ContentArea RollingBannerArea { get; set; }

+1! count my voice too

Hi!

We are currently working on fixing the known issues for the AllowedTypes pattern and will try to include this functionality as the same time. So if you are lucky you get a nice christmas present :).

Hi,

Did the ability to disable the "Create new" and only allow drag and drop of existing blocks get added as suggested above?  I have exactly the same requirement here.

Thanks

Gary

Hi Gary,

I don't think that it's a built in functionality in EPi9, but tt's not difficult to implement.

Here is a detailed description:

https://gregwiechec.com/2016/05/how-to-disable-creating-new-blocks-in-content-area/