Issue: [4.1 Alpha 2] Add page to category no permission error

It would be helpful to know which demo categories you have attempted this with, since different categories might have different states (different area, protected, etc), and this could contribute or at least provide insight into the direction of the problem:
The specific categories are also helpful because there are multiple permissions which intersect here:
- Permission (at the page) to add this page to categories generally
- Permission (at the category) to add pages to that specific category

Good point. I experienced the permission errors when trying to add the above "Template Line Dropping" page to the category "categorieën" in Alternate Area 3
And then I tried creating my own category page "Big category test" in System, which went fine, but suffered the same permission issue when adding pages to it:
I tried adding pages at least from System and Demo areas to "Big category test", all unsuccessfully.

I see that your user has permissions of:
- Page Permissions > Can add pages to categories = YES
- Category Permissions > Can add entries to Categories = NO

So the page would not prevent you from putting it into a category, but no categories will accept that. So the correct behavior would be that you cannot add content to categories.

So at first glance, it looks like the error message is correct.
Now we have different questions:

Should you be able to see the category editor? If you have custom permissions for another area where the second permission is on, then yes, because you would be able to add to categories that exist in the other area. If you don't, but if you have permission to remove existing listings from categories (you DO have: Category Permissions > Can remove entries from Categories = YES), then you would see the category editor.

Since you don't have add permissions from the category side, the editor should not be offering those categories as add-choices. I believe this is the bug we are seeing.

Now if there are no areas that would have categories accept new listings from you, but there are categories allowing you to remove existing listings, then I think the design of the editor needs to be improved, because it does not currently make a distinction here, and that is another issue that should be corrected. In this (your) case, the category editor should still show, but it should not provide any controls allowing you to add new categories -- only the current/remove sections should be shown.

Thanks for the reply. Right, there's not much point suggesting the categories where user permissions wouldn't allow the add entries action.

I see, I think that sounds right. Having the form adapt to the user permission combination (add entries YES/NO & remove entries YES/NO) would be an improvement, for sure. But there could be a further improvement, too. In a situation where a user would only have the ability to remove a page from a category but not add, if the page isn't listed in any categories currently, then the AJAX form pencil edit button next to "Categories: None" would be unnecessary.

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One other potential improvement here, long term, could be during new category creation itself. It would be a reasonable assumption that someone making a new category probably intends on attaching pages to it at some point . I don't remember seeing any warning/notice while creating "Big category test" in the VW XF demo System area that my permission combination wouldn't allow adding pages to it. While I'm not suggesting that new category creation should be blocked, having some kind of indicator of suitable Areas might be good.

The following should be fixed in the next build:
- When the user has permission to view a page that has moderated edits but does not have permission to view moderated edits, the page's status icon uses the moderated color. In the next build, the icon will instead use the appropriate new/old color for those users.

Assuming the following condition:
The user has no permission to add listings to any categories and; the page has no categories or the user has no permission to remove listings from any categories.

The following should be fixed in the next build:
- Don't show category editor or its pencil icon.
- When attempting to access do=categorize, throw a permission error.
- For the category editor's New Category button, only offer areas where the user has permission to also add listings to categories.
- For choosers for other container-types (books, feeds, etc), the New [Container] button has similarly been fixed so that only areas where the user has permission to also add to the container are offered.

In the next release:
- If the category editor still appears, don't show the add-category portion of the category editor when the user has no permission to add listings to any categories.