Comment # 13 on bug 954623 from Wolfgang Bauer

(In reply to Mark Fairbairn from comment #11)
> Created attachment 662681 [details]
> blank tray space and xembed crash

Hm? Where's a crash there?

> However, there is a blank space beside the dropbox icon. This seems to be a
> separate issue to the ongoing blank space icon problem with system tray in
> plasma 5 which can be corrected by toggling settings.

No.
This seems to be an issue of fcitx itself.
It apparently creates an XEmbed icon as well which is empty, and this is what
made xembedsniproxy crash in the first place.
The fix prevents the crash, and now the empty icon is added to the system tray.

I see something similar in IceWM as well btw: Often (not always) a blank window
appears (old-style system tray icons are just regular application windows that
are embedded in the system tray via XEmbed) in addition to the (new-style?)
icon in the system tray, which even prevents me from logging out.

If you see this as bug, please report it separately against fcitx.

Closing as fixed.