We're working on a multiplatform game for Android and iOS in HaXe / NME, and are building to the Windows / C++ target for debug and testing. Everything pretty much works perfectly, except that trace output only appears in FlashDevelop's output window once the built app has been closed?

Does anyone know if there's a way to get the app to send its traces to FD's output window in real time?

Weird thing is that it's using the regular process runner which is used everywhere else in FD. I've tried to workaround it but I can't seem to find a way to get the output progressively...

Works fine when executed from a command prompt though.

Forgive my ignorance, but how would I execute the debug build from a command prompt?

I presume you don't mean just navigating to the compiled exe from a dos prompt and running it?

Command prompt ("DOS prompt") is always an option. However, you can automate it with FD help.
Put this into your Project -> Properties -> Run Custom Command...

When you run your project, you'll get a separate console window with all the output.

Aha.. excellent I'll give it a try. thanks.

Facing the same issue.
In FD 4.0 using the command line was an okay work-around, but would love to have it in output.
Tried it in FD 4.1 (dev) and I get no output when I use trace(); it all stays buffered until I close the program.

So compiling for windows still creates an issue, but I discovered I can receive Flash traces if I use Lib.trace().
My issue was omitting Lib., because while trace() compiles; it doesn't give you output in Flash.

Apparently Joshua has fixed this issue in NME SVN.