Thank you answers, meanwhile I found a workaround :)
My text edit dialog always open, attached to the
main window, so it shows the current text always.
It's okay, now.
But (a new request follows ;) the dialogs disappear
when the main window lose the focus. Now, inkscape
gets a whole virtual desktop, so it is not a problem,
but it would be very kind to get an option to off
this feature (in future, not too important one).