Questions to the PBVision and PBTREE

1. - Lostfocus for a textbutton in PB Vision and PBTree.

How can I know when a text button loses the focus?.
How can I know when the key Enter or was Tab pressed in a text button (keypress)?.
In the ide he/she gives the powerbasic GETEVENT(0) it returns 219, 219, 403 when you jumps he/she gives a
text button to other, but I need to know which fué the previous control that he/she obtained the focus
(or I need to use a flag every time that a control obtains the focus to keep it).

2. - is there some restriction in the use he/she gives PBVision and PBTREE together?.
Where I should declare PBTREE in a created program with the WorkShop?

3. - in my code of program:
type letrareg
letter as string*10
importe(1 to 6) as double
end type

dim letter as letrareg
get kaestcta%,nreg&,letra

valor #= using $(" ########. ##,letra.importe(3)/100)

it happens an error 9 or 208

I have had to change the line for: valor# = cvd(mid$(letra,23,8)) so that it doesn't generate error
What am I making bad?

Thank you for any help that you can give me