Is https://github.com/bitshares/bitshares-ui the place where such issues should be reported?

Yes.

I am really not sure, because on https://testnet.bitshares.eu/ the interface looks a bit different, without basic mode and without deposit possibilities.

testnet.bitshares.eu is not up-to-date, and there are no deposit possibilities because you wouldn't want to deposit real BTC on a testnet that can break down anytime.

For my own peace of mind I have tried to move 7 BTS back to Coinbase to see how the process works. I exchanged the 7 BTS to OPEN.BTC and then withdrew the OPEN.BTC to my Coinbase address. In that withdrawal process it appeared that the OPEN.BTC was converted back to BTC for the transfer. The transfer went through with no error (at least I think it did) however nothing has showed up in my Coinbase account yet.

Note that the BTC mining fee of .0003 BTC will be paid from the amount you are withdrawing. A microscopic transfer like yours might not be sufficient to cover all fees. Not sure if coinbase has a minimum deposit amount for BTC.

You can check your deposit address at blockchain.info to see if OL executed the transfer.

nobody ever told me about these rule.

Who told you that the margin call would be filled at the lower price? I guess nobody did. It's just an assumption on your side.

I admit that it's a *reasonable* assumption, and that this is how it *should* work. But the fact that it doesn't is not a bug. It's just the way it has been implemented, and AFAIK it does not violate the specification.

It's not the only point where the market engine does not behave how people assume it does, see the case brought up by @alexpmorris a couple of months ago. The market engine needs an overhaul, but that is something that takes care, and planning, and detailed specifications, and lots of discussion. You don't do someting like this overnight.

Shorters should know that they risk a 10% penalty when being margin called. None of the defined operational parameters are broken through this behaviour.
IMO this bug is a flaw, but not a serious problem. It certainly doesn't justify an emergency fix, or whatever you expect.

Many users would also feel more comfortable using this if a BitShares dev peer reviewed the code.  That would also help iron out any bugs and speed development.  Perhaps Alfredo or Abit could help with this?

AFAICS this project will only use the API. IMO Abit's and Alfredo's is better spent on the core.

I am new to bitshares. I asked for settlement of bitUSD.  I think i have misunderstood what that means. I dont have any long or short positions. And I am unclear what the 'fair price' means at that time. DO i get bitshare according to the price which will be there at the time 24 hours after i placed the order? I thought it is at the time when i put in the order.

How Do i cancel the settlement order?

You will receive 99% of the settlement price at the time when settlement happens, i. e. 24 hours after requesting settlement.

It is not possible to cancel settlement requests.

maybe the following link is the answer to my question.
http://docs.bitshares.eu/api/wallet-api.html#account-calls

That's a good start, yes.

the bitsharetalk community is too inactive!

What? Because nobody answered your question within an hour? And you even had to look for answers yourself, that's so 90s!

   2) From the graph interface, we should set the maximal asset limit. could I issue an user asset without maximal limit?

No, that's technically not possible. You have 15 decimal digits available, and you can choose where to set the decimal point.

  3) what is the cost to issue one user asset? and what is the cost to transfer user asset between two users?

The current fees can be viewed here: https://bitshares.openledger.info/explorer/fees
Transferring as well as issuing assets currently costs 0.22 BTS plus 0.12 BTS per kilobyte.
Creating an asset is a lot more expensive. The price depends on the length of the asset symbol.

The issue was submitted a long ago, why wasn't the fix included in the last fork?

We discussed the fixes to be included in the hardfork here: https://bitsharestalk.org/index.php/topic,24816.0.html

At that time, the problem was only a side remark on issue #338. There several reasons why it wasn't included, like
* lack of manpower (at the time, @oxarbitrage was the only paid developer)
* the problem was not considered to be a serious one
* nobody came up and asked for a fix, or offered to help - as you can see from that thread, general interest from the community was almost non-existant
* we have a lot of issues regarding the market engine, so fixing this should be part of a bigger overhaul IMO