I finally encountered what appears to getting this in this mode.
If you highlight some text and then execute a surround (whatever / menu or command line), it appears that all subsequent slickedit command mode commands will always use a dialogue pop up rather than allowing you to tab through the options.
That is, I'm using vim emulation, so when I press ^A to get the slickedit command line and then say want to open a file (e.g., 'e foo<tab>'), it will now always use a dialogue rather than show the drop down of the available options and allow <tab> to cycle through the options (or editing of the command).
The only way I've seen to revert it back to this is the kill the vs_exe process so that whatever configuration change was made with the surround selection isn't saved.
I'd still like to know what the configuration parameter is to change it back, and also think this is a bug as it appears that the option is changed on the fly and not reverted back.