Problem: Slow redrawing with DirectX.
Solution: Avoid calling gui_mch_flush() unnecessarily, especially when
updating the cursor. (Ken Takata, closes#2560)
Problem: DirectX scrolling can be slow, vertical positioning is off.
Solution: Make scroll slightly faster when using "scrlines:1". Fix y
position of displayed text. Fix DirectX with non-utf8 encoding.
(Ken Takata, closes#2440)
Problem: MS-Windows: does not show colored emojis.
Solution: Implement colored emojis. Improve drawing speed. Make 'taamode'
work. (Taro Muraoka, Yasuhiro Matsumoto, Ken Takata, close#2375)
Problem: Gcc error for the argument of InterlockedIncrement() and
InterlockedDecrement(). (Axel Bender)
Solution: Remove "unsigned" from the cRefCount_ declaration.
Problem: Text drawing on newer MS-Windows systems is suboptimal. Some
multi-byte characters are not displayed, even though the same font
in Notepad can display them. (Srinath Avadhanula)
Solution: Add the 'renderoptions' option to enable Direct-X drawing. (Taro
Muraoka)
