why does focus on fld doesn't focus the field?

[Tiemo Hollmann TB]

Hello,

I have a scrolling field "foo", where I loose the focus when clicking into
field "foo", selecting the clicked line and calling some handlers and
filling other fields. My first idea was to focus on field "foo" at the end
of mouseUp to get the focus on field "foo" again in case the focus get lost
somewhere in the other handlers. But keyUp and keyDown don't work, the
cursor just stays on the same line. Additionally to the focus I have to
select line x of field "foo". (select line word 2 of the selectedline of fld
"foo"  of fld "foo") Now KeyUp and KeyDown work again. My question is: why
do you need a select line additionally to the focus to get the keys work
again? Even if actually a line still was selected. Is it a bug or just rev
logic or just a knot in my brain?

Thanks Tiemo