Using the following script, reduce the window size.
The right adjusted text simply disappears from the display.

(Could both centered and right adjusted wrapping algorithms (for text) be much simpler?)

package require Tk

set fixedFont {"Courier New" -12}

frame .f -width 100 -height 20
pack .f -side left
text .t -font $fixedFont -width 40 -height 10
pack .t -expand 1 -fill both

.t configure -wrap char -highlightthickness 0 -borderwidth 0 -padx 0 -pady 0

.t delete 1.0 end
.t configure -width 40 -padx 0 -highlightthickness 0 -border 0
update
.t tag configure x -tabs [list 280]
.t tag configure y -tabs [list 280 center]
.t tag configure z -tabs [list 280 right]
.t insert 1.0
.t insert end
.t insert end
.t insert end
    .t tag add x 1.0 2.0
    .t tag add y 2.0 3.0
    .t tag add z 3.0 4.0