FileDialog filter inconsistency

[ACrazyTown]

Originally reported on the OpenFL discord.

The documentation for the filter argument in FileDialog.save() says:

A filter to use when browsing. Asterisks are treated as wildcards. For example, "*.jpg" will match any file ending in .jpg. Used only if targeting deskop.

My understanding is that I should pass in something like *.png to show just PNG files, but doing that seems to not be right (at least on Windows) and it tries to browse for files that end in *.*.png. I have to pass in png to get the desired results.

It was later determined that FileDialog.cpp adds the *. prefix automatically:

lime/project/src/ui/FileDialog.cpp

Lines 258 to 259 in bc8f9df

	std::wstring temp (L"*.");
	const wchar_t* filters[] = { filter ? (temp + *filter).c_str () : NULL };

Is this a mistake in the docs or a bug?