+ if {$i == 0} {
+ # draw the link to the first child as part of this line
+ incr row -1
+ set child [lindex $displayorder $row]
+ set ccol [lsearch -exact [lindex $rowidlist $row] $child]
+ if {$ccol >= 0} {
+ set x [xc $row $ccol]
+ set y [yc $row]
+ if {$ccol < $col - 1} {
+ lappend coords [xc $row [expr {$col - 1}]] [yc $row]
+ } elseif {$ccol > $col + 1} {
+ lappend coords [xc $row [expr {$col + 1}]] [yc $row]
+ }
+ lappend coords $x $y
+ }
+ }
+ if {[llength $coords] < 4} return
+ set last [expr {[llength $idrowranges($id)] / 2 - 1}]
+ if {$i < $last} {
+ # This line has an arrow at the lower end: check if the arrow is
+ # on a diagonal segment, and if so, work around the Tk 8.4
+ # refusal to draw arrows on diagonal lines.
+ set x0 [lindex $coords 0]
+ set x1 [lindex $coords 2]
+ if {$x0 != $x1} {
+ set y0 [lindex $coords 1]
+ set y1 [lindex $coords 3]
+ if {$y0 - $y1 <= 2 * $linespc && $x1 == [lindex $coords 4]} {
+ # we have a nearby vertical segment, just trim off the diag bit
+ set coords [lrange $coords 2 end]
+ } else {
+ set slope [expr {($x0 - $x1) / ($y0 - $y1)}]
+ set xi [expr {$x0 - $slope * $linespc / 2}]
+ set yi [expr {$y0 - $linespc / 2}]
+ set coords [lreplace $coords 0 1 $xi $y0 $xi $yi]
+ }
+ }
+ }
+ set arrow [expr {2 * ($i > 0) + ($i < $last)}]
+ set arrow [lindex {none first last both} $arrow]