I ’ ve suggestion with list of available dabases in Databases combo. You list only databases from local client, but usualy users are connected to remote database , and list of available connections could be inadequate to the real state of connections on remote database. So maybe it would be usfull to sign this list as “databases from local settings”, and add list of hosts from existing dblinks on the curent database, marking that this is list of currently used hosts.
select distinct upper(host) from all_db_links
Think about this.
By the way , as I wrote in on of previous threads , in current connection list , local listener is listed too, and should be removed