treectrl and item bbox

[Googie]

Hi,

I'm trying to place [entry] widget on treectrl cell (it's configured to
work as a datagrid) and I get its (the cell) coordinates by:

set geom [$tree item bbox $item_id $column_id]

when I use it:

place $frame_widget \
-x [lindex $geom 0] \
-y [lindex $geom 1] \
-width [expr {[lindex $geom 2]-[lindex $geom 0]}] \
-height [expr {[lindex $geom 3]-[lindex $geom 1]}]

I can see, that my frame widget is placed about 2 pixels on the right
from the correct position and about 2 pixels down from the correct
position.

What is the reason and what is the solution?

Thanks for help!

--
Pozdrawiam (Greetings)!
Googie