And another whilst waiting after having dragged the crop's bottom-right corner to a new location:

Program received signal SIGINT, Interrupt.
0x00007ffff546f31d in fsync () from /lib/x86_64-linux-gnu/libpthread.so.0
(gdb) bt
#0  0x00007ffff546f31d in fsync () from /lib/x86_64-linux-gnu/libpthread.so.0
#1  0x00007ffff602e46e in full_fsync (fd=<optimised out>, fullSync=<optimised out>, dataOnly=<optimised out>) at sqlite3.c:26201
#2  unixSync (id=0x8884b0, flags=<optimised out>) at sqlite3.c:26290
#3  0x00007ffff6054050 in sqlite3OsSync (flags=<optimised out>, id=<optimised out>) at sqlite3.c:15004
#4  syncJournal (newHdr=1, pPager=0x8882b8) at sqlite3.c:41288
#5  syncJournal (pPager=0x8882b8, newHdr=1) at sqlite3.c:41216
#6  0x00007ffff60557f5 in pagerStress (pPg=0xbea420, p=0x8882b8) at sqlite3.c:41572
#7  pagerStress (p=0x8882b8, pPg=0xbea420) at sqlite3.c:41529
#8  0x00007ffff600e7b7 in sqlite3PcacheFetch (pCache=0x8883c0, pgno=19429, createFlag=createFlag@entry=1, 
    ppPage=ppPage@entry=0x7fffffffca98) at sqlite3.c:35302
#9  0x00007ffff603eabf in sqlite3PagerAcquire (pPager=0x8882b8, pgno=pgno@entry=19429, ppPage=ppPage@entry=0x7fffffffca98, 
    noContent=noContent@entry=0) at sqlite3.c:42374
#10 0x00007ffff603ec78 in btreeGetPage (pBt=pBt@entry=0x887df8, pgno=pgno@entry=19429, ppPage=ppPage@entry=0x7fffffffcad8, 
    noContent=noContent@entry=0) at sqlite3.c:49871
#11 0x00007ffff604b9d9 in getOverflowPage (pBt=pBt@entry=0x887df8, ovfl=ovfl@entry=19429, ppPage=ppPage@entry=0x7fffffffcb18, 
    pPgnoNext=pPgnoNext@entry=0x7fffffffcb14) at sqlite3.c:52118
#12 0x00007ffff604f18c in clearCell (pPage=pPage@entry=0x8991f8, pCell=<optimised out>) at sqlite3.c:53620
#13 0x00007ffff6053a51 in sqlite3BtreeInsert (pCur=<optimised out>, pKey=pKey@entry=0x0, nKey=<optimised out>, pData=0x2c70358, 
    nData=<optimised out>, nZero=<optimised out>, appendBias=0, seekResult=0) at sqlite3.c:55208
#14 0x00007ffff607f617 in sqlite3VdbeExec (p=p@entry=0xdeeee8) at sqlite3.c:68076
#15 0x00007ffff6063341 in sqlite3Step (p=0xdeeee8) at sqlite3.c:62221
#16 sqlite3_step (pStmt=0xdeeee8) at sqlite3.c:62295
#17 sqlite3_step (pStmt=pStmt@entry=0xdeeee8) at sqlite3.c:62282
#18 0x000000000042fb02 in autosave_manager_update_page (self=<optimised out>, page=0x6b52d0) at autosave-manager.c:1423
#19 0x00007ffff65b4620 in g_closure_invoke () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#20 0x00007ffff65c5f00 in ?? () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#21 0x00007ffff65cdd11 in g_signal_emit_valist () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#22 0x00007ffff65ce4b9 in g_signal_emit_by_name () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#23 0x0000000000418259 in page_view_motion (self=0x6b5360, x=x@entry=307, y=<optimised out>) at page-view.c:3400
#24 0x00000000004125b7 in book_view_motion_cb (event=<optimised out>, widget=<optimised out>, self=0x86d190) at book-view.c:2003
#25 _book_view_motion_cb_gtk_widget_motion_notify_event (_sender=<optimised out>, event=0xa22410, self=0x86d190) at book-view.c:236
#26 0x00007ffff78af5ac in ?? () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0
#27 0x00007ffff65b48e7 in ?? () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#28 0x00007ffff65cd2df in g_signal_emit_valist () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#29 0x00007ffff65cdf92 in g_signal_emit () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#30 0x00007ffff79de77e in ?? () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0
#31 0x00007ffff78ad44e in ?? () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0