it looks just like the CTRL-SHIFT-V list from VA, of the items in the clipboard. there are no icons, which seems to rule out completion or suggestion listboxes.
I can get something close to this, by typing a comma in an existing function call, which produces the parameter information tooltip. If I them press CTRL-SHIFT-SPACE while this tooltip is there then the VA clipboard menu appears.
For me these are appearing next to each other.
When you took this screen shot was the caret very close to the top or the bottom of the screen? Which IDE are you using?