real nice (Error) text-popup

just last week I saw in a script a very nice error popup (only text one gives, if I remember correct)

did not noted it how it was done (Blender 2.58? )
Who either gives me the link or the code?

Thanks in advance

thanks RickyBlender … you are right
the code with va.op0 or so contains what I saw :wink: I will see how to use it my latest ‘meander’ project …