I have the following plugins loaded: Address Keeper, Bogofilter, Fancy HTML Viewer, and Notification.

When I select 'Notification' from the plugin list and click 'Unload', the plugin is successfully unloaded. Then, when I click 'Load...' to load a different plugin, CM is killed.

I can load another plugin after having unloaded 'Notification' by first closing and then reopening the 'Plugins' dialog.


Below you will find the out from running CM in gdb, unloading 'Notification' and finally clicking on 'Load...':

~ gdb claws-mail
GNU gdb (GDB) 7.6.1-ubuntu
Copyright (C) 2013 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-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /usr/bin/claws-mail...Reading symbols from /usr/lib/debug/.build-id/d5/f456937a74bad565e02a2da3380839f940bef0.debug...done.
done.
(gdb) run
Starting program: /usr/bin/claws-mail 
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7fffeaaf5700 (LWP 10588)]
[New Thread 0x7fffea2f4700 (LWP 10589)]
[New Thread 0x7fffe9af3700 (LWP 10590)]
[New Thread 0x7fffd12b9700 (LWP 10673)]

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff74070d6 in ?? () from /usr/lib/x86_64-linux-gnu/libgtk-x11-2.0.so.0
(gdb) 



Below you will find full stacktrace as output by gdb:
(gdb) backtrace full
#0  0x00007ffff74070d6 in ?? () from /usr/lib/x86_64-linux-gnu/libgtk-x11-2.0.so.0
No symbol table info available.
#1  0x00007ffff6efa94d in ?? () from /usr/lib/x86_64-linux-gnu/libgdk-x11-2.0.so.0
No symbol table info available.
#2  0x00007ffff6efc1a8 in ?? () from /usr/lib/x86_64-linux-gnu/libgdk-x11-2.0.so.0
No symbol table info available.
#3  0x00007ffff6efc24e in ?? () from /usr/lib/x86_64-linux-gnu/libgdk-x11-2.0.so.0
No symbol table info available.
#4  0x00007ffff4efa3b6 in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
No symbol table info available.
#5  0x00007ffff4efa708 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
No symbol table info available.
#6  0x00007ffff4efab0a in g_main_loop_run () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
No symbol table info available.
#7  0x00007ffff720cf62 in gtk_dialog_run () from /usr/lib/x86_64-linux-gnu/libgtk-x11-2.0.so.0
No symbol table info available.
#8  0x00000000005e348e in filesel_create (title=<optimized out>, path=path@entry=0x6db298 "/usr/lib/x86_64-linux-gnu/claws-mail/plugins/", multiple_files=multiple_files@entry=1,
    open=open@entry=1, folder_mode=folder_mode@entry=0, filter=filter@entry=0x6e0011 "*.so") at filesel.c:166
        slist = 0x0
        slist_orig = 0x0
        list = 0x0
        action = <optimized out>
        action_btn = <optimized out>
        chooser = 0xfff0c0
#9  0x00000000005e39a5 in filesel_select_multiple_files_open_with_filter (title=<optimized out>, path=path@entry=0x6db298 "/usr/lib/x86_64-linux-gnu/claws-mail/plugins/",
    filter=filter@entry=0x6e0011 "*.so") at filesel.c:214
No locals.
#10 0x000000000062055e in load_cb (button=<optimized out>, pluginwindow=0xb88e50) at pluginwindow.c:200
        file_list = <optimized out>
#11 0x00007ffff51c33b7 in ?? () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
No symbol table info available.
#12 0x00007ffff51dbe82 in g_signal_emit_valist () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
No symbol table info available.
#13 0x00007ffff51dcae2 in g_signal_emit () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
No symbol table info available.
#14 0x00007ffff71e1625 in ?? () from /usr/lib/x86_64-linux-gnu/libgtk-x11-2.0.so.0
No symbol table info available.
#15 0x00007ffff51c33b7 in ?? () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
No symbol table info available.
#16 0x00007ffff51dbe82 in g_signal_emit_valist () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
No symbol table info available.
#17 0x00007ffff51dcae2 in g_signal_emit () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
No symbol table info available.
#18 0x00007ffff71e0569 in ?? () from /usr/lib/x86_64-linux-gnu/libgtk-x11-2.0.so.0
No symbol table info available.
#19 0x00007ffff7282645 in ?? () from /usr/lib/x86_64-linux-gnu/libgtk-x11-2.0.so.0
---Type <return> to continue, or q <return> to quit---
No symbol table info available.
#20 0x00007ffff51c3188 in g_closure_invoke () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
No symbol table info available.
#21 0x00007ffff51d48db in ?? () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
No symbol table info available.
#22 0x00007ffff51dc4f9 in g_signal_emit_valist () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
No symbol table info available.
#23 0x00007ffff51dcae2 in g_signal_emit () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
No symbol table info available.
#24 0x00007ffff73925f4 in ?? () from /usr/lib/x86_64-linux-gnu/libgtk-x11-2.0.so.0
No symbol table info available.
#25 0x00007ffff7280df4 in gtk_propagate_event () from /usr/lib/x86_64-linux-gnu/libgtk-x11-2.0.so.0
No symbol table info available.
#26 0x00007ffff72811ab in gtk_main_do_event () from /usr/lib/x86_64-linux-gnu/libgtk-x11-2.0.so.0
No symbol table info available.
#27 0x00007ffff6efc27c in ?? () from /usr/lib/x86_64-linux-gnu/libgdk-x11-2.0.so.0
No symbol table info available.
#28 0x00007ffff4efa3b6 in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
No symbol table info available.
#29 0x00007ffff4efa708 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
No symbol table info available.
#30 0x00007ffff4efab0a in g_main_loop_run () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
No symbol table info available.
#31 0x00007ffff7280277 in gtk_main () from /usr/lib/x86_64-linux-gnu/libgtk-x11-2.0.so.0
No symbol table info available.
#32 0x0000000000449442 in main (argc=1, argv=0x7fffffffdb58) at main.c:1551
        connection = 0xa1d5e8
        error = 0x0
        nm_proxy = 0xa05b10
        userrc = <optimized out>
        mainwin = 0xa57610
        folderview = 0xbbce00
        icon = 0xa288a0
        crash_file_present = <optimized out>
        num_folder_class = <optimized out>
        asked_for_migration = <optimized out>
        start_done = <optimized out>
        plug_list = 0x0
        never_ran = <optimized out>
        mainwin_shown = <optimized out>
        start = {tv_sec = 1397724990, tv_usec = 146348}
        end = {tv_sec = 1397724990, tv_usec = 466616}
        diff = {tv_sec = 0, tv_usec = 320268}
        timing_name = 0x6484ad "startup"
        __FUNCTION__ = "main"
(gdb)


I use CM from the ubuntu ppa; apt-cache reports thusly:
~ apt-cache policy claws-mail claws-mail-multi-notifier
claws-mail:
  Installed: 3.9.3-1ubuntu1ppa1~saucy1
  Candidate: 3.9.3-1ubuntu1ppa1~saucy1
  Version table:
 *** 3.9.3-1ubuntu1ppa1~saucy1 0
        500 http://ppa.launchpad.net/claws-mail/ppa/ubuntu/ saucy/main amd64 Packages
        100 /var/lib/dpkg/status
     3.8.1-2 0
        500 http://de.archive.ubuntu.com/ubuntu/ saucy/universe amd64 Packages
claws-mail-multi-notifier:
  Installed: 3.9.3-1ubuntu1ppa1~saucy1
  Candidate: 3.9.3-1ubuntu1ppa1~saucy1
  Version table:
 *** 3.9.3-1ubuntu1ppa1~saucy1 0
        500 http://ppa.launchpad.net/claws-mail/ppa/ubuntu/ saucy/main amd64 Packages
        100 /var/lib/dpkg/status
     3.8.1-2ubuntu2 0
        500 http://de.archive.ubuntu.com/ubuntu/ saucy/universe amd64 Packages



I do not run CM in a desktop environment such as gnome, nor kde, nor xfce.