Make a plugin for XFCE that opens/closes appfinder similar to a menu
I know this sounds like "let's do a Whisker menu clone", but appfinder is already great at finding apps, and it also supports categories + right click actions for icons. It is simple yet powerful enough to be used as a menu. You can add a launcher for it to any panels (easy) but clicking it will open the window at the center of the screen if that's setup in XFCE for all windows, or under the mouse pointer if this is, again, setup system wise.
But if appfinder is to be used via the mouse and also keyboard I think the best would be to open it at the center of the screen when used with a key-binding, and close to the launcher when it is clicked.
Key-binding -> center of the screen
Launcher -> close to the launcher
In this video is a demo of how it would look like (if the user clicks the launcher and the appfinder window opens at the center of the screen, it is a bit annoying/unexpected):
This may be out of scope for appfinder, but I thought is worth mentioning. We had a discussion here about this possibility https://forum.xfce.org/viewtopic.php?pid=65071