I have the SYS packages shown in the object browser.
I have focus on the first package amgt$datapump.
I type the characters "dbms_".
Now three packages are selected: DBMSHSXP, DBMSZEXP_SYSPKGGRNT, DBMS_ADDM
where I expected only DBMS_ADDM to be marked.
If I e.g. right-click on the package DBMS_ADDM and select View, all three (marked) packages are opened.
The work-around is to click on another package that is not marked and then click on the package that you want, then everything works as expected.
It is not a big thing, but a funny behaviour that has been around since version 11 or 12, so if it can be fixed, I would appreciate it.