After commit 2aa54a90, a double-byte character is sent to the edit control by double WM_CHAR messages. However, its WM_CHAR handler (ANSI version) can't process a double-byte character properly because the handler converts WM_CHAR to WCHAR one by one.
This fix queues the double-byte lead byte as it comes in and then uses it afterwards for the WCHAR conversion.
Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=54337
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https://gitlab.winehq.org/wine/wine/-/merge_requests/1992