SUMMARY
Kmail v5.10.0.

Opens OK, opens a letter OK, then when I close the Close button on a letter window Kmail crashes.


STEPS TO REPRODUCE
1. Open KMail
2. Open a letter in a seperate window
3. Close window

OBSERVED RESULT
Application crashes

EXPECTED RESULT
Application sh.not crash and has to continue.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: PCLinuxOS 64bit
KDE Plasma Version: 5.14.4.1-1pclos2018 
KDE Frameworks Version: 5.53.0
Qt Version: 5.11.3
windows system xcb.

ADDITIONAL INFORMATION
[as@localhost ~]$ gdb kmail
gdb: Symbol `acs_map' has different size in shared object, consider re-linking
GNU gdb (GDB) 7.8-1pclos2014 (PCLinuxOS release 2014)
Copyright (C) 2014 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-mandriva-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from kmail...(no debugging symbols found)...done.
(gdb) run
Starting program: /usr/bin/kmail 
warning: Could not load shared library symbols for linux-vdso.so.1.
Do you need "set solib-search-path" or "set sysroot"?
warning: File "/lib64/libthread_db-1.0.so" auto-loading has been declined by your `auto-load safe-path' set to "$debugdir:$datadir/auto-load".
To enable execution of this file add
        add-auto-load-safe-path /lib64/libthread_db-1.0.so
line to your configuration file "/home/as/.gdbinit".
To completely disable this security protection add
        set auto-load safe-path /
line to your configuration file "/home/as/.gdbinit".
For more information about this security protection see the
"Auto-loading safe path" section in the GDB manual.  E.g., run from the shell:
        info "(gdb)Auto-loading safe path"
warning: Unable to find libthread_db matching inferior's thread library, thread debugging will not be available.
org.kde.pim.kmail: Delaying instance creation.
org.kde.pim.kmail: Starting up...
org.kde.pim.mailtransport: "971519311"
org.kde.pim.mailtransport: "557864784"
org.kde.pim.mailtransport: "1648815112"
org.kde.pim.mailtransport: 
org.kde.pim.kmail: KMail init with akonadi server state: 2
Connection to speech-dispatcher failed
Connection to speech-dispatcher failed
Connection to speech-dispatcher failed
Connection to speech-dispatcher failed
Connection to speech-dispatcher failed
Connection to speech-dispatcher failed
Connection to speech-dispatcher failed
Connection to speech-dispatcher failed
Connection to speech-dispatcher failed
[New LWP 7755]
[New LWP 7751]
org.kde.pim.messageviewer: No Header Style plugin found !
org.kde.pim.messageviewer: No Header Style plugin found !
org.kde.pim.messageviewer: No Header Style plugin found !
org.kde.pim.kmail: Initting systray
org.kde.pim.mailtransport: 
org.kde.pim.kmail: A Resource started to synchronize, starting a mail check.
org.kde.pim.kmail: Last resource finished syncing, mail check done
org.kde.pim.kmail: void KMReaderWin::setMessage(const Akonadi::Item&, MimeTreeParser::UpdateMode) QSplitter(0xa9de60, name="splitter2")
org.kde.pim.messageviewer: trying to writeMessageHeader() without a header style set!
org.kde.pim.mailtransportakonadi: Fetching collection 69
org.kde.pim.mailtransportakonadi: Traversing 0 items.
org.kde.pim.mailtransportakonadi: No subjobs; I am done
org.kde.pim.mailtransportakonadi: succeeded.
qt.qpa.xcb: QXcbConnection: XCB error: 8 (BadMatch), sequence: 1573, resource id: 71303214, major code: 130 (Unknown), minor code: 3
qt.qpa.xcb: QXcbConnection: XCB error: 8 (BadMatch), sequence: 1587, resource id: 71303214, major code: 130 (Unknown), minor code: 3
qt.qpa.xcb: QXcbConnection: XCB error: 8 (BadMatch), sequence: 1592, resource id: 71303214, major code: 130 (Unknown), minor code: 3
qt.qpa.xcb: QXcbConnection: XCB error: 8 (BadMatch), sequence: 1608, resource id: 71303214, major code: 130 (Unknown), minor code: 3
org.kde.pim.kmail: void KMReaderWin::setMessage(const Akonadi::Item&, MimeTreeParser::UpdateMode) QSplitter(0xa9de60, name="splitter2")
org.kde.pim.messageviewer: trying to writeMessageHeader() without a header style set!
Connection to speech-dispatcher failed
Connection to speech-dispatcher failed
Connection to speech-dispatcher failed
Connection to speech-dispatcher failed
org.kde.pim.messageviewer: No Header Style plugin found !
org.kde.pim.messageviewer: No Header Style plugin found !
org.kde.pim.kmail: void KMReaderWin::setMessage(const Akonadi::Item&, MimeTreeParser::UpdateMode) KMReaderMainWin(0x17a2700, name="readerwindow#1")
org.kde.pim.messageviewer: trying to writeMessageHeader() without a header style set!

<comment: now the letter window is open>
<comment: and now I press Close windows button in the right upper corner of the window:>

QIODevice::read (QLocalSocket): device not open
QIODevice::read (QLocalSocket): device not open
QIODevice::read (QLocalSocket): device not open

Program received signal SIGSEGV, Segmentation fault.
0x00000000018e3a50 in ?? ()