Steps to reproduce:
1. Start dia
2. In the toolbox window, click on the Text icon.
3. In the new diagram window, click once to add a text object.
4. When the text object has been added and still selected press the Delete key.


Stack trace:
*** glibc detected *** dia: free(): invalid pointer: 0x0af5dd20 ***
======= Backtrace: =========
/lib/libc.so.6[0xca9f18]
/lib/libc.so.6(__libc_free+0x78)[0xcad3ef]
/usr/lib/libglib-2.0.so.0(g_free+0x31)[0x12d5a1]
dia(diagram_unselect_object+0x2d)[0x805e2bd]
dia(diagram_unselect_objects+0x77)[0x805e397]
dia[0x806597e]
dia(edit_delete_callback+0x42)[0x806c5d2]
/usr/lib/libgobject-2.0.so.0(g_cclosure_marshal_VOID__VOID+0x49)[0x2aa1d9]
/usr/lib/libgobject-2.0.so.0(g_closure_invoke+0x12b)[0x29cf8b]
/usr/lib/libgobject-2.0.so.0[0x2ade3d]
/usr/lib/libgobject-2.0.so.0(g_signal_emit_valist+0x8c7)[0x2af347]
/usr/lib/libgobject-2.0.so.0(g_signal_emit+0x29)[0x2af509]
/usr/lib/libgtk-x11-2.0.so.0[0x2b1d285]
/usr/lib/libgtk-x11-2.0.so.0[0x2b1e3c4]
/usr/lib/libgobject-2.0.so.0(g_closure_invoke+0x12b)[0x29cf8b]
/usr/lib/libgobject-2.0.so.0[0x2ade3d]
/usr/lib/libgobject-2.0.so.0(g_signal_emit_valist+0x68f)[0x2af10f]
/usr/lib/libgobject-2.0.so.0(g_signal_emit+0x29)[0x2af509]
/usr/lib/libgtk-x11-2.0.so.0(gtk_accel_group_activate+0xd9)[0x2b19589]
/usr/lib/libgtk-x11-2.0.so.0(gtk_accel_groups_activate+0xfa)[0x2b1968a]
/usr/lib/libgtk-x11-2.0.so.0(gtk_window_activate_key+0xea)[0x2cf497a]
/usr/lib/libgtk-x11-2.0.so.0[0x2cf49ec]
/usr/lib/libgtk-x11-2.0.so.0[0x2bf758e]
/usr/lib/libgobject-2.0.so.0[0x29b7a9]
/usr/lib/libgobject-2.0.so.0(g_closure_invoke+0x12b)[0x29cf8b]
/usr/lib/libgobject-2.0.so.0[0x2ae483]
/usr/lib/libgobject-2.0.so.0(g_signal_emit_valist+0x68f)[0x2af10f]
/usr/lib/libgobject-2.0.so.0(g_signal_emit+0x29)[0x2af509]
/usr/lib/libgtk-x11-2.0.so.0[0x2ce2858]
/usr/lib/libgtk-x11-2.0.so.0(gtk_propagate_event+0x1ba)[0x2bf0f9a]
/usr/lib/libgtk-x11-2.0.so.0(gtk_main_do_event+0x317)[0x2bf21b7]
/usr/lib/libgdk-x11-2.0.so.0[0x7d585a]
/usr/lib/libglib-2.0.so.0(g_main_context_dispatch+0x16d)[0x12615d]
/usr/lib/libglib-2.0.so.0[0x1293ef]
/usr/lib/libglib-2.0.so.0(g_main_loop_run+0x1a9)[0x129799]
/usr/lib/libgtk-x11-2.0.so.0(gtk_main+0xb4)[0x2bf2634]
dia(main+0x3f)[0x809e66f]
/lib/libc.so.6(__libc_start_main+0xdc)[0xc5b724]
dia[0x805da71]
======= Memory map: ========
00101000-00192000 r-xp 00000000 16:03 2804944    /usr/lib/libglib-2.0.so.0.1000.3
00192000-00193000 rwxp 00091000 16:03 2804944    /usr/lib/libglib-2.0.so.0.1000.3
00195000-001e6000 r-xp 00000000 16:03 2826703    /usr/lib/libcairo.so.2.2.4
001e6000-001e7000 rwxp 00051000 16:03 2826703    /usr/lib/libcairo.so.2.2.4
001e7000-001e8000 r-xp 00000000 16:03 2866871    /usr/lib/gconv/ISO8859-1.so
001e8000-001ea000 rwxp 00000000 16:03 2866871    /usr/lib/gconv/ISO8859-1.so
001ea000-001ee000 r-xp 00000000 16:03 3037937    /usr/lib/gtk-2.0/2.4.0/loaders/libpixbufloader-png.so
001ee000-001ef000 rwxp 00003000 16:03 3037937    /usr/lib/gtk-2.0/2.4.0/loaders/libpixbufloader-png.so
001ef000-001f6000 r-xp 00000000 16:03 3291750    /usr/local/lib/dia/libdxf_filter.so
001f6000-001f7000 rwxp 00007000 16:03 3291750    /usr/local/lib/dia/libdxf_filter.so
001f7000-001fc000 r-xp 00000000 16:03 3291720    /usr/local/lib/dia/libchronogram_objects.so
001fc000-001fe000 rwxp 00004000 16:03 3291720    /usr/local/lib/dia/libchronogram_objects.so
001fe000-00206000 r-xp 00000000 16:03 3291736    /usr/local/lib/dia/libcgm_filter.so
00206000-00207000 rwxp 00007000 16:03 3291736    /usr/local/lib/dia/libcgm_filter.so
00207000-0020b000 r-xp 00000000 16:03 3291746    /usr/local/lib/dia/libsvg_filter.so
0020b000-0020c000 rwxp 00004000 16:03 3291746    /usr/local/lib/dia/libsvg_filter.so
0020c000-00239000 r-xp 00000000 16:03 3291762    /usr/local/lib/dia/libvdx_filter.so
00239000-0023a000 rwxp 0002d000 16:03 3291762    /usr/local/lib/dia/libvdx_filter.so
0023a000-0023d000 r-xp 00000000 16:03 3291748    /usr/local/lib/dia/libshape_filter.so
0023d000-0023e000 rwxp 00003000 16:03 3291748    /usr/local/lib/dia/libshape_filter.so
0023e000-00246000 r-xp 00000000 16:03 3291712    /usr/local/lib/dia/libfs_objects.so
00246000-00248000 rwxp 00008000 16:03 3291712    /usr/local/lib/dia/libfs_objects.so
00248000-0024b000 r-xp 00000000 16:03 3291724    /usr/local/lib/dia/libmisc_objects.so
0024b000-0024c000 rwxp 00002000 16:03 3291724 Aborted


Other information:
Platform: Fedora Core 5