Re: Error while selecting from combobox

Am 11.02.25 um 08:40 schrieb alexandru:

This is random error, could not be reproduced yet.
 It happend while the user selected a value from a ttk::combobox.
 There is a trace to the combobox variable, added with: trace add
variable $varname write $callback
 But the error does not seem to have anything with the callback function.
 It's a rather internal issue.
 Any ideas?
 Thanks
Alex
  *** END OF ERROR MESSAGE ***} -errorlog 1}
1: {::bgerrorhandler
{Index 2 out of range}
{-code 1
-level 0
-errorstack
    {INNER {invokeStk1
vpan.main.workframe.detailsframe.sw.sf.mf.cf.asmpar.solve.cb3 current
2}
    CALL {SelectEntry
vpan.main.workframe.detailsframe.sw.sf.mf.cf.asmpar.solve.cb3 2}
    CALL {LBSelect
vpan.main.workframe.detailsframe.sw.sf.mf.cf.asmpar.solve.cb3.popdown.f.l}
    CALL {ttk::combobox::LBSelected
vpan.main.workframe.detailsframe.sw.sf.mf.cf.asmpar.solve.cb3.popdown.f.l}
}
-errorcode
    {TTK COMBOBOX IDX_RANGE}
-errorinfo
    {Index 2 out of range
    while executing
"$cb current $index"
    (procedure "SelectEntry" line 2)
    invoked from within
"SelectEntry $cb [lindex $selection 0]"
    (procedure "LBSelect" line 5)
    invoked from within
"LBSelect $lb"
    (procedure "ttk::combobox::LBSelected" line 3)
    invoked from within
"ttk::combobox::LBSelected
vpan.main.workframe.detailsframe.sw.sf.mf.cf.asmpar.solve.cb3.popdown.f.l
"
    (command bound to event)} -errorline 1}}
0: {::meshparts::showstack file2a8350dd0}
--

The reported issue is easy to reproduce:
set cb [ttk::combobox .cb -state readonly -values {a b c}]
$cb current 0
pack $cb -padx 20 -pady 20
after 5000 { $cb configure -values {a b}; puts "value list changed" }
Pop down the listbox associated with the combobox *immediately*, wait until you see the message "value list changed", and then click on the last list element.  As a result, an error dialog will pop up, displaying the following message:
index "2" out of range
index "2" out of range
     while executing
"$cb current $index"
     (procedure "SelectEntry" line 2)
     invoked from within
"SelectEntry $cb [lindex $selection 0]"
     (procedure "LBSelect" line 5)
     invoked from within
"LBSelect $lb"
     (procedure "ttk::combobox::LBSelected" line 3)
     invoked from within
"ttk::combobox::LBSelected .cb.popdown.f.l "
     (command bound to event)
I suspect that your application does something similar, namely it manipulates the value list while the user is selecting a value.  To prevent such situations, the application should not be allowed to change the values if the listbox is popped down, i.e., if the following holds true:
     [winfo exists $cb.popdown] && [winfo ismapped $cb.popdown]
--
Csaba Nemethi  https://www.nemethi.de  mailto:csaba.nemethi@t-online.de