File picker error - 'File does not exist' on XFCE

When attempting to send a file via HTTP Upload, sometimes the file selection fails. When you select a file, you get a "File does not exist" error dialog. Closing the file picker and re-trying (with the same file!) fixes it.

I usually only send single files, so that's when I've usually encountered it. Haven't tried with multiple files.

I'll post debug log output when I encounter it again. If I remember correctly, the log contained a GTK error of some sort.

• Gajim v1.0.99+bdd243d0 / gajim-default-nightly, 20180930-1
• XFCE 4.12.3
• Debian 9.5 (stretch)
• Linux debian 4.9.0-8-686 #1 (closed) SMP Debian 4.9.110-3+deb9u5 (2018-09-30) i686 GNU/Linux