What causes the Talent/Glyph/Reforge UIs to break?

[espoire]

So, I'm sure many people have seen it: You go to swap a talent and get "RandomAddon has been prevented from accessing a secure... blah blah blah". It blames a random addon each time, and I seem to be incapable of reproducing the problem on purpose with all my addons running. Yet, it's a common occurrence during raid night. I know /reloadui is a workaround, but I'm seeking a permanent fix.

A Google search offers a ton of reasons, all of which aren't true (based on my testing.) This is likely because the returned posts are multiple years out of date.

Anyone have any idea what causes or fixes it?

[Deleted]

Keeping your addons up to date should help fix it. I havent seen this problems for months now.

[Deleted]

Playing in fullscreen and tabbing out during the loading screen nearly always causes it to be broken for me.

[cremor]

You could try this addon:
http://www.curse.com/addons/wow/notaint

It even explains the most common causes of the problem in its description.

[SpaceDuck]

most common taints are caused when an addon uses a blizzard function. for example there is UIFrameFlash, which will allow you to make something fade in or out. when the addon registers its own frame with this function, blizzards code will add this frame to a big table (or list) of all the frames that need to be flashed along side all of blizzards frames that require flashing

now blizzards code is very over protective, when it goes through the table to check if the frame you just put up needs flashing, it will see your addons frame in the list and goes "hm, this isnt a blizzard frame, thus it must be an attempt to hack my code!". To counter this "attempt" to "hack" the code, blizzards UI code will block all actions from everything in the list, including your talent frame, your glyph frame etc

hope that explains what you asked!

[ComputerNerd]

UIFrameFlash is depreciated, and simply should have been removed ages ago.
That would fix that problem easily, if you cannot use it and would be forced to find an alternative.
Most of the issues are blizzard being stubborn and choosing to blame addon authors rather than looking closer to home.

There are multiple addons around to fix game bugs, some of which have been around at least for the full length of this expansion, and some way longer than that.
StrataFix, BlizzBugsSuck being two examples I use myself.