>>>Or what you'd call stress.
>>>
>>>Someone (in Microsoft) coined the phrase "accented characters". Well, no, it's all wrong. Accent is on the whole syllable, precisely on the vowel in that syllable, not on any particular character. And then, in most languages, the accent is actually not written at all, except in some special cases when it needs to be pronounced in a non-standard way, or when the word could have a different meaning depending on where's the accent (as in proDUce vs PROduce - but I wouldn't know how to write the accent in that case).
>>>
>>>The author of this idiocy has confused the diacriticals (i.e. signs used for modifying the characters, above, below or as a strike) with accents (aka stress). So to this person ž is an accented character. I would very much like this person to pronounce it with and without stress and have the difference measured on today's sound analyzers. Also, I'd like to know how this person perceives the different kinds of stress/accent when we pronounce c, č and ć. Or, in case of hungarian language, to explain to the natives that they are wrong in thinking that they always putting accent on the first syllable, when in many words (like rendeztő, betegség etc) they put the accent near the end of the word.
>>>
>>>Does anyone know who originated this misconception? I'd like this accented character to be brought forward.
>>
>>In Spanish of Spain, they call these characters 'tilde' instead of 'acento' indicating that it is simply a character that goes above a letter.
>
>This is tilde: ~, aka chr(126). And IIRC they also have a dieresis on e when it's to be read as e and not according to/in combination with the preceding vowel. They're lucky they have only two, and even that is enough to have their words mistyped and accused of having "accented characters". "Pronounce that loud and clear boy, I specially want to hear that accent on en".

The Spaniards refer to tilde not only for the character 126 but to any accent mark. For example, to distinguish 'mas' y 'más' and a few other cases where the word changes meaning depending if it has a tilde/accent or no. They just refer as tilde in general sense not specifically referring to this character.