I'm running KDE and use Oxygen-GTK theme for GTK applications. Downgrading oxygen-gtk2 Arch package to version 1.2.1-1 solves problem.

It is strange because:
1) I have 2 PCs running Arch with different video cards and both have this problem with Deluge
2) No other applications on both PCs work like this

Ok. Thanks for assistance. Hope, I'll manage to find some solution: Deluge is very convenient bittorrent client for me.

Sorry GNU gdb (GDB) 7.4 Copyright (C) 2012 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Type "show copying&quo...

GNU gdb (GDB) 7.4 Copyright (C) 2012 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Type "show copying" an...

I'm running Arch Linux The program 'deluge-gtk' received an X Window System error. This probably reflects a bug in the program. The error was 'BadWindow (invalid Window parameter)'. (Details: serial 48496 error_code 3 request_code 155 minor_code 3) (Note to programmers: normally, X errors are report...