The tray icon and font size are too small under HiDPI desktop

[asouchang]

The tray icon and font size of fcitx are too small under Xfce with 2.0 scale factor (WindowScalingFactor under GDK in xsetting) in HiDPI monitor.

Neither explicitly setting GDK_SCALE nor QT_SCALE_FACTOR to 2 works. It seems fcitx doesn't respect any one of scaling environment variable.

Setting Xft.dpi in .Xresources doesn't seems an option because it makes Xfce's font being scaled twice meanwhile the fcitx tray icon is not scaled at all.

Any advises?

https://i.imgur.com/KzILlGb.png