Set listbox transparency in Yosemite

I found this great thread on setting a window’s transparency in Yosemite.

https://forum.xojo.com/16453-window-transparency-vibrancy

I’d like to extend that translucency to a listbox I have along the left edge of the window (like the Finder window, Mail, and iTunes). Is that possible with Xojo and declares?

https://forum.xojo.com/16981-transparency-for-listboxes-so-they-would-work-with-osx-10-10-vi