I just reproduced this problem also, on Linux 64-bit, also with Beta 6:
SlickEdit 2013 (v18.0.0.10 64-bit)
Serial number: FE26181_BETA
License type: Beta License
License expiration: 2013-07-15 10:03:00
License file: /opt/slickedit/bin/slickedit.lic
Build Date: May 30, 2013
Emulation: Visual Studio
OS: Linux
OS Version: Debian GNU/Linux 7.0 (wheezy)
Kernel Level: 3.9.4-<user>-<hostname>
Build Version: #1 SMP Fri May 24 14:22:08 PDT 2013
Processor Architecture: x86_64
X Server Vendor: The X.Org Foundation
Memory: 63% Load, 18118MB/28732MB Virtual
Shell Info: /bin/bash -i
Screen Size: 2560 x 1600, 1920 x 1200
Project Type: Gnuc
Language: No file open
Installation Directory: /opt/slickedit/
Configuration Directory: /home/<user>/.slickedit/18.0.0/
Spill File: /tmp/$slk.<user>.26555