I'm trying to display current username in prompt via:
prompt $E]9;8;"USERNAME"$E\

However, if I use it, while current Username is indeed displayed, the text reflow is broken — when I enter a long command that doesn't fit in one line, instead of continuing to the 2nd line I start from the same line (the prompt text and the previous text of the command get overwritten) and only with the next line does the text flows to the next line (so it's visually 2nd line although it's supposed to be 3rd).
See the screenshot below: notice there is no Username on the left, multiple pastes of the same test "LongCommandText" just continues on the SAME line instead of jumping down to the second.

Similar thing happens when I invoke a long command from history (with Up) — prompt text gets overwritten and I lose some of the text in the beginning (instead, when I use Left to reach the beginning, there is a bunch of white spaces displayed instead of actual text).
Also, another visual artifact: if I invoke a command (even some short one) from history and go back to no command (i.e. Up then Down or just try to delete the whole line), I still get some text displayed in my prompt (see screenshot below, where "prompt $E]9;" shouldn't be there, it's a command from history that I can't delete)

System:
CMDer 1.2.9
ConEmu 160228 [32]
Windows 10.0.10586