WowAce

What steps will reproduce the problem?
1.  Load BetterBlizzOptions
2. Open the Interface options for any addon
3. Click the "Defaults" button in the bottom left-hand corner
4. Notice the confimation dialog pops up "behind" the InterfaceOptionsFrame, where it cannot be clicked.

What is the expected output? What do you see instead?
I expect StaticPopup confirmation dialogs launched from InterfaceOptionsFrame to appear above it, not beneath it. The same problem happens with any addon-specific StaticPopup_Show() commands launched from InterfaceOptionsFrame (eg by an AceConfig execute button).

What version of the product are you using?
r39-release

Please provide any additional information below.

The problem is caused by LibBetterBlizzOptions-1.0.lua:132:

InterfaceOptionsFrame:SetFrameStrata("FULLSCREEN_DIALOG")

which changes the default InterfaceOptionsFrame strata from "HIGH" (which is below StaticPopup that runs at "DIALOG") to "FULLSCREEN_DIALOG" which is above StaticPopup.

I don't see a good reason for the library to messing with the InterfaceOptionsFrame strata, especially in light of the fact that it breaks StaticPopup behavior.
The fix is to remove that line.

Fixed in lib r6.