#2153 textDisp test case failure on cvs head

[Larry W. Virden]

solaris 2.9 sun c compiler build of tk 8.5 cvs head;
test suite displayed via exceed 10.0.0.12 on a win xp
system.

textDisp.test

==== textDisp-27.7 SizeOfTab procedure, center
alignment, wrap -none (potential
numerical problems) FAILED
==== Contents of test case:

.t delete 1.0 end
set cm [winfo fpixels .t 1c]
.t configure -tabs {1c 2c center 3c 4c 5c 6c 7c 8c}
-wrap none -width 40
.t insert 1.0
a\tb\tc\td\te\n012345678934567890a\tbb\tcc\tdd
set width [expr {$fixedWidth * 19}]
set tab $cm
while {$tab < $width} {
set tab [expr {$tab + $cm}]
}
# Now we've calculated to the end of the tab after
'a', add one
# more for 'bb\t' and we're there, with 4 for the
border. Since
# Tk_GetPixelsFromObj uses the standard 'int(0.5 +
float)' rounding,
# so must we.
set tab [expr {4 + int(0.5 + $tab + $cm)}]
update
set res [.t bbox 2.23]
lset res 0 [expr {[lindex $res 0] - $tab}]
set res

---- Result was:
-36 18 7 13
---- Result should have been (exact matching):
-28 18 7 13
==== textDisp-27.7 FAILED

[Larry W. Virden]

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user_id=15949
Originator: YES

this identical behavior continues to manifest with the beta tcl/tk 8.5 cvs head.