I've been running WS 6.5.3 for a couple months now under Ubuntu 9.04 (Jaunty), and just upgraded to Ubuntu 9.10 (Karmic) with kernel 2.6.31. After that, VMWare WS wasn't correctly grabbing input (mouse and keyboard); it seemed to be fighting with my window manager or something. Moving the mouse would cause the cursor to flicker, and keyboard input worked intermittently. The border around the viewport that shows when it's accepting input would also flicker. After some searching, I found this thread:

http://communities.vmware.com/message/1398149

So I set VMWARE_USE_SHIPPED_GTK=yes, and then got some undefined symbol errors when starting vmware. That led me to this thread:

http://communities.vmware.com/message/1380852

which suggestedusing LD_PRELOAD to get the right libglib loaded before starting vmware.

I've added the last two lines in my /etc/vmware/bootstrap and things seem to work well:

export VMWARE_USE_SHIPPED_GTK=yes
export LD_PRELOAD=/lib/libglib-2.0.so.0