I open a browser window with menu File, Script files, Practice file ...
Then choose (for example) the Gretl tab.
The first entry receives focus and one can move within the window with Arrow down, arrow up, Home and End.
Pgdn also works and does what one expects.
However the PgUp key shows weird behaviour.
If the focus is not on the last file then PgUp behaves like PgDn(??).
When the focus i son the last file pressing PgUp does nothing; I expect the focus to move up in the list.