To set this up here's the version and settings I'm using (I'm also displaying the default quest tracker with a few quests in it):
http://imgur.com/YbjZrHD
I'm running zero other addOns during this test to eliminate any interference from outside sources. To record the taintLog I'm using "/console taintLog 2", /reloading, opening and closing oQueue, and getting the full taintLog on logout to track down why when I click a quest item it sometimes blocks it from the quest watcher frame.
Here's the result (Generally speaking the tainting action comes just above the tainted Blizzard Global variable WATCHFRAME_NUM_POPUPS.)
http://imgur.com/13JdasW
That Global variable is called by Blizzard for the quest tracker (Watch Frame) and since it's tainted by oQueue it's no longer secure and when clicking a quest item in the quest tracker can produce an action blocked by addon error message and fail.
What I do when I'm coding to check for potential taint is turn on "/console taintLog 2" then after zoning in or running all functions of my addon then open the taint.txt file and search for "watchframe" (the quest tracker), "uidropdown" (the right click dropdown menu that can affect raid frames/talent/glyph changes), "fcf" (the floating chat frames which eventually taints the uidropdown system and macro system) and "block" (this being a protected function or post-tainted function). I find that most of the time searching for those 4 words in the taint log can direct me to the taint and it's generally the action or two right above it.
Looks like it's related to OQMainFrame. Could be what needs to happen is copying Blizzard's code and then re-using it locally. Several authors do this with the UIDropDown system to avoid tainting it while still being able to use it.
Keep up the good work.
