When I slide the transparency slider, Guake doesn't turn transparent, it just applies a gray background.

Have you try to reinstall? I just install Guake three or four days ago and the transparancy working properly
im using Ubuntu 18.04

Have you try to reinstall? I just install Guake three or four days ago and the transparancy working properly
im using Ubuntu 18.04
Still doesn't work :(
Fixed, need to change Compositor Rendering Backend settings.

Most helpful comment
Fixed, need to change Compositor Rendering Backend settings.
