I tried to fix up a launcher for sqldeveloper.

I entered the path as

/usr/local/bin/sqldeveloper
then I get a message and process that never ends

"setting up system" with endless progress widgets

The Updating System Configuration windows can be buggy sometimes, however they can be safely closed without harm to your system. Once you have finished making your changes, run "kbuildsycoca" manually on the terminal if you encounter any out of date information with the launcher.

ancient low level controvery

which "path" is entered?

/usr/local/bin/sqldeveloper my guess
/usr/local/bin/

right click in the desktop...add widgets...then what

I tried to several widgets onto the desktop and that failed...I got the mail fedora dialog (lower left "f"