Repro with:
Version: 6.0.0.0.alpha1+
Build ID: b3f1d199a72ce87cb65ddaeac922564f57da6a4d
CPU threads: 4; OS: Windows 6.3; UI render: GL; 
TinderBox: Win-x86@42, Branch:master, Time: 2017-11-06_00:10:53
Locale: nl-NL (nl_NL); Calc: CL

and not with:
Version: 5.4.1.0.0+
Build ID: f200d5700782ae179fd96b6ad4b0fe8e7edd1616
CPU threads: 4; OS: Windows 6.29; UI render: default; 
Locale: nl-NL (nl_NL); Calc: CL

I'll try to reproduce this but if someone may provide a bt it could be useful.

Let's increase importance too since it's a crash + regression.

On pc Debian x86-64 with master sources updated today (0d50804e1c0c0ea2a5cd73fa3fa2a9ff0a0e7048), with gen rendering (so the nearest one of Windows), I don't reproduce this.

This happens with other icons as well, for example Insert Basic Shapes. 
Additionally, even if you do not undock BOTH toolbars, but only the one where the icon/button is, if you click the icon/button twice, the app crashes.

This seems to have begun at the below commit.
Adding Cc: to Justin Luth ; Could you possibly take a look at this one?
Thanks
 364381eb6bf7bdd6d01edf4ac9f68a9ff7c2efb5 is the first bad commit
commit 364381eb6bf7bdd6d01edf4ac9f68a9ff7c2efb5
Author: Norbert Thiebaud <nthiebaud@gmail.com>
Date:   Sat Sep 30 13:48:45 2017 -0700

    source 892c719fffa06de4c7aeab497326cad7bae9e5c6
author    Justin Luth <justin_luth@sil.org>    2017-09-21 00:44:01 (GMT)
committer    Justin Luth <justin_luth@sil.org>    2017-09-27 01:59:33 (GMT)
commit    892c719fffa06de4c7aeab497326cad7bae9e5c6 (patch)
tree    4c7107df4428492ddb1a4a2edfc3aafa5ea30a6f
parent    465092047d5fa6ec6dd369372e712d76554570ff (diff)
Revert "tdf#108932 - prevent textbox shrink from actually growing"

(In reply to raal from comment #5)
Highly unlikely that a unrelated, revert of a recent commit would cause this. Better retest and start before 2017-08-31.

After the changes done by Caolán, is this issue still reproducible in master?

@Emil, @raal, is this issue still reproducible in master?

I can reproduce it in 

Version: 6.1.0.0.alpha0+ (x64)
Build ID: 04982dc8f56e3a960b4d42b0ec57fc5cb8a01aa3
CPU threads: 1; OS: Windows 6.1; UI render: default; 
TinderBox: Win-x86_64@42, Branch:master, Time: 2017-12-04_01:29:50
Locale: ja-JP (ja_JP); Calc: group threaded

(In reply to Emil Tanev from comment #9)
> I can reproduce it in 
> 
> Version: 6.1.0.0.alpha0+ (x64)
> Build ID: 04982dc8f56e3a960b4d42b0ec57fc5cb8a01aa3
> CPU threads: 1; OS: Windows 6.1; UI render: default; 
> TinderBox: Win-x86_64@42, Branch:master, Time: 2017-12-04_01:29:50
> Locale: ja-JP (ja_JP); Calc: group threaded

Could you please get a backtrace as explained here: https://wiki.documentfoundation.org/How_to_get_a_backtrace_with_WinDbg ?

I guess the bisection is incorrect

Repro with
Version: 6.1.0.0.alpha0+
Build ID: ef22c4a0a99be5d2903fb9e9d09fc852cd791173
CPU threads: 4; OS: Windows 6.3; UI render: default; 
TinderBox: Win-x86@42, Branch:master, Time: 2018-01-12_09:16:04
Locale: nl-NL (nl_NL); Calc: CL

Assertion failed!

Program: C:\LibO1novDebug\program\vcllo.dll
File: C:/cygwin/home/tinderbox/master/vcl/win/app/salinst.cxx
Line: 625

Expression: !pInst->mbNoYieldLock

Created attachment 139095 [details]
backtrace

Yes, this is an assert, which means even if it's a regression it's not bibisectable in Windows (removing keywords for now, Telesto if your 5.4.1.0.0+ build is debug one, feel free to readd keywords regression and notBibisectable). Attaching backtrace.

No longer reproduced in

Versión: 6.2.0.2
Id. de compilación: 2ce5217b30a543f7666022df50f0562f82be0cff
Subprocs. CPU: 1; SO: Windows 6.1; Repres. IU: predet.; VCL: win; 
Configuración regional: es-ES (es_ES); Idioma de IU: es-ES
Calc: threaded

@Emil Tanev, please double-check

Closing as RESOLVED WORKSFORME