[Tcl-bugs] [ tktoolkit-Bugs-3006842 ] Empty tag bindings crash ttk::treeview

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Bugs item #3006842, was opened at 2010-05-25 05:48
Message generated for change (Comment added) made by jenglish
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Category: 88. Themed Tk
Group: current: 8.5.8
Status: Open
Resolution: None
Priority: 7
Private: No
Submitted By: Steven (stevenaaus)
Assigned to: Joe English (jenglish)
>Summary: Empty tag bindings crash ttk::treeview

Initial Comment:
This may be a very minor windows only bug, but activestate tcl-8.5.8.2 (WinXP) crashes immediately when i assign a null binding to button-1 on a treeview widget, and click on the widget.
The code that causes it is
  $w.tree tag bind click1 <Button-1> {}
When using click1 as a tag such as
  $w.tree insert {} 0 -values $values -tag [list click1 click2 treefont]

Problem is easily solved by removing null binding.

Sorry for such a shitty bug report, but it may be interesting to someone

Project is scidvspc , subversion release 42
http://scidvspc.svn.sourceforge.net/viewvc/scidvspc?view=rev&revision=42





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>Comment By: Joe English (jenglish)
Date: 2010-05-27 12:23

Message:
Apparently Tk_BindEvent() does not like it if an empty script is passed to
Tk_CreateBinding().  This is the apparent cause of the coredump.

Other widgets (text, canvas) interpret [$w tag foo <...> {}] to mean
"remove this tag binding entirely"; ttk::treeview widget updated to do the
same.

Additionally: the [text] and [canvas] widgets can be made to crash by
appending an empty script to a binding:

pack [text .t]
.t tag bind empty <ButtonPress-1> +
.t insert end "CLICK ME" empty


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Comment By: Steven (stevenaaus)
Date: 2010-05-25 15:47

Message:
I had a go at reproducing it with the 8.5 tk demo
" 4. A multi-column list of countries"
and it is easily reproducible here.
To make the demo crash make these changes.

+ $w.tree tag bind click1 <Button-1> {}
foreach {country capital currency} $data {
-  $w.tree insert {} end -values [list $country $capital $currency]
+ $w.tree insert {} end -values [list $country $capital $currency] -tag
click1
and click on treeview.

Using 
+ $w.tree tag bind click1 <Button-1> {puts ok}
is fine.
-----------------------------------------
[
Can anyone tell me how to figure out how many ttk_treeview rows are in a
widget after it has been resized. I think i saw that "treeview configure
-rowheight" is in cvs... but is there another way
I currently use:

set fontspace [font metrics [ttk::style lookup [$w cget -style] -font]
-linespace]
set fontspace [expr $fontspace*120/72] ; # hack to make it work better
set num_rows [expr {int( [winfo height $w] / $fontspace)}]
]

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Comment By: Joe English (jenglish)
Date: 2010-05-25 09:55

Message:
Nope, I haven't seen this before, and it hasn't been fixed.  

The treeview widget is apparently not using Tk_BindEvent() et. al., in the
way in which they were designed to be used.  More than that I cannot say at
this time; will look into it later.

Thanks for the bug report, it's actually quite useful.

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Comment By: Joe English (jenglish)
Date: 2010-05-25 09:41

Message:
I think I've seen this before.  I thought it was fixed.  Will check.

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