well, it depends
LB302 and from 0.4.8 also zynAddSubFX has portamento posibillities. So direct setting slide-notes on piano-roll -as in FL-studio, is not posible, but if you use either of the two plugings LB302 or zynAddSubFX, you can have portameto /glissando 'slides' on your notes.
If you install VSTige instruments, most of these has setting for porta, but with these instruments you cant automate anything.
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