I have some (maybe) stupid question.
My app has some (out of combat) invisible frames.
What I want is to show them up when I enter the config dialog and set them back to original stat when leaving the config dialog.
Is there some "OnClose" callback I missed? Or is this not possible?
local cfgDlg = LibStub("AceConfigDialog-3.0")
You can do a toggle on the window opening as you've shown there, calling the frames shown before opening the window. but wrt closing it no.. that's not going to easily happen with out weird magic hackery.
Best sugestion is to add an additional option to your config table that will toggle the config mode, it's a common practice.