Greyshades:I think the simple grammatical answer is just this:

Pro is followed by a noun
Cxar is followed by a clause

well, yes, you're right. I think I'm deliriously tired. Why did I even get involved in this discussion about 'Cxar' vs. 'Pro'?!

'because' = cxar (or "pro tio, ke").
"because of/due to" = pro.

If it helps, you could think of 'pro tio, ke' in terms of the formal English expression "due to the fact that"...

Tommjames explained everything perfectly well in the second post of this thread. Why didn't I just read that first?!

I suppose I just saw 'pro tio, cxar..." and that really freaked me out. I really have problems with this expression. Surely, it's wrong?! I just had a look in PMEG and it's not there.

Hello!

Chainy:Germans would probably say "wofuer" (like in old English "wherefore") or "wieso" (literally "why so")

Common German words for "kial" are "warum" and "wieso".

Compounds literally equivalent to "pro kio" are "weswegen" ("wegen" = "pro") and "weshalb" ("halber" is a less common word for "pro" and used as a postposition).

On the other hand, "wofür" means "por kio".

Kolonjano

KoLonJaNo:Hello!

Chainy:Germans would probably say "wofuer" (like in old English "wherefore") or "wieso" (literally "why so")

Common German words for "kial" are "warum" and "wieso".

Compounds literally equivalent to "pro kio" are "weswegen" ("wegen" = "pro") and "weshalb" ("halber" is a less common word for "pro" and used as a postposition).

On the other hand, "wofür" means "por kio".

Kolonjano

With all of these options in German, I get into a real muddle! That's probably why I stick to 'warum'!

In fact, I've often thought about how I prefer to say "pro tio, ke" instead of "Cxar". For me, the former roles of the tongue quite nicely, whereas I sometimes find 'Cxar' doesn't fit in so nicely with the flow of the sentence. But this is just personal preference. Ultimately, I don't think it makes any difference which way you choose to say 'because'.

Chainy:I suppose I just saw 'pro tio, cxar..." and that really freaked me out. I really have problems with this expression. Surely, it's wrong?!

PMEG would seem to agree with you; at this page we find "La varianton *pro tio ĉar* oni tamen ne uzu."

"Pro tio ĉar" sure seems strange and pointless to me but there do seem to be a fair number of results in Google for it. Perhaps some other languages have a similar construction?

Hello!

tommjames:"Pro tio ĉar" sure seems strange and pointless to me but there do seem to be a fair number of results in Google for it. Perhaps some other languages have a similar construction?

Indeed.

In German you could encounter "deswegen|deshalb" (= "pro tio") and "weil" (= "char") in a sentence, e.g.

Sie tat das deswegen, weil sie ihn liebte.

(= Shi faris tion pro tio, char shi amis lin.)

However, leaving out "deswegen" wouldn't change the meaning, just be less emphatic.

On the other hand, "pro tio ke" (= "deswegen dass") is something a German learning Esperanto might have to get used to.

Strangely enough, "trotzdem dass" (= "malgrau tio ke") is actually used in place of "obwohl" (= "kvankam") by some people, though.

Kolonjano

qwertz:Okay, back to topic. Seems to be that you can use both together.

Stano MARČEK "Esperanto per rekta metodo" paĝo 78:

Pro

Pro kio ŝi ploras? Ŝi ploras, ĉar ŝi estas malfeliĉa. Pro kio vi venis? Pro tio, ĉar mi volis vidi vin. Pro unu arbo li arbaron ne vidas. Pro kio vi ridas? Pro tio, ĉar mi aŭdis bonan anekdoton. Li amas tiun* knabinon pro tio, ke ŝi estas bona kaj bela.

PRO KIO = KIAL | PRO TIO=TIAL

Edit:* tion to tiun

I attached the regarding page. The author of this learning book is from Slovakia. Maybe it's different point of view(?). I don't know. Mi estas komencanto.

KoLonJaNo:
Strangely enough, "trotzdem dass" (= "malgrau tio ke") is actually used in place of "obwohl" (= "kvankam") by some people, though.

Worse, some people use phrases like:
*Ich ging weg, trotzdem ich nicht alles fertig gemacht hatte
(just as erroneous as in English "I went away despite that I hadn't finished everything").