Description:
I created a document with lots of cut&paste operation and editing. Now Writers hangs, when I try to delete some specific line breaks.

Steps to Reproduce:
Environment: MS Windows 10, 64 bit, LibreOffice 7.0.4

I started with four new Writer-documents and a text source.

The text source is a data export from „telegram“ messenger using Telegram Desktop. The export function created a directory tree. Each chat gets a sub-folder with a HTML-file and further sub-folders for photos and voice messages. I opened the HTML-files with a double-click which uses Microsoft Edge Version 90.0.818.41 on my computer.

I used three intermediate Writer documents which I filled via copy&pasted from the char protocols in the edge windows.

The main document has a few lines of introduction and then a table with two columns and many rows. I entered plain text in some of the cells of the left side. I filled the columns on the right side with fragments of the chat protocols by using cut&paste. In a first phase I moved longer runs of the protocol from the inter mediate files into table cells. The I used → Tabelle → Einfügen → oberhalb und → Tabelle → Einfügen → unterhalb quite often and moved parts of the text of existing cells into new cells. Then I started to delete some parts. After several hours Write hang (endless loop occupien one core of my 4 core CPU). I had to kill the program and recover the document. When trying to countiue editing Write hang more and more often. Finally I had a document, which I could open and Write hang after deleting a single linebreak. 

Upgrading to 7.1.1.2 did not help.

Storing the document as .docx and starting from there did not help.

Storing the document as .html truncated the document. So I have a document with many hours of work, which I cannot use any longer.

The document is some 28 pages long. Technically I would be able to repair the .html-document using a text-editor to recover at least ¾ of the document. But with 340 Kbytes of HTML I will not start trying.


I assume that the document has several structural errors which got worse and ever worse during editing. 

I am sorry but because of the private content I cannot send in the document. And as the document cannot be edited any longer I cannot remove private text fragments any longer.

Also I do not know how to look at the internal structure used by Writer.

Looking for the origin I found one spot:
The HTML created by the “telegram desktop” tool contained something like:

<div class="media_wrap clearfix">
. <a class="media clearfix pull_left block_link media_voice_message" href="../../chats/chat_04/voice_messages/audio_1@11-04-2021_12-41-51.ogg">
. . <div class="fill pull_left">
. . </div>
. . <div class="body">
. . . <div class="title bold">
. . . . Voice message
. . . </div>
. . . <div class="status details">
. . . . 01:10
. . . </div>
. . </div>
. </a>
</div>

(line breaks and dots inserted by me.)

When I copy&paste the whole html-file into an new Writer document and save that as .html and search for the corresponding location, I find:

<p style="margin-left: 2.91cm; margin-bottom: 0cm; line-height: 100%">
. <spacer type="block" align="left" width="48" height="48">
. . <span style="display: inline-block; border: none; padding: 0cm">
. . . <span style="font-variant: normal">
. . . . <font color="#212121">
. . . . . <span style="text-decoration: none">
. . . . . . <font face="Open Sans, Lucida Grande, Lucida Sans Unicode, Arial, Helvetica, Verdana, sans-serif">
. . . . . . . <font size="2" style="font-size: 10pt">
. . . . . . . . <span style="letter-spacing: normal">
. . . . . . . . . <span style="font-style: normal">
. . . . . . . . . . <b>
. . . . . . . . . . . Voice message
. . . . . . . . . . </span>
. . . . . . . . . </b>
. . . . . . . . </span>
. . . . . . . </span>
. . . . . . </font>
. . . . . </font>
. . . . </span>
. . . </font>
. . </span>
. </p>
. <p style="margin-bottom: 0cm; line-height: 100%">
. . <span style="display: inline-block; border: none; padding: 0cm">
. . . <span style="font-variant: normal">
. . . . <font color="#70777b">
. . . . . <span style="text-decoration: none">
. . . . . . <font face="Open Sans, Lucida Grande, Lucida Sans Unicode, Arial, Helvetica, Verdana, sans-serif">
. . . . . . . <font size="2" style="font-size: 9pt">
. . . . . . . . <span style="letter-spacing: normal">
. . . . . . . . . <span style="font-style: normal">
. . . . . . . . . . <span style="font-weight: normal">
. . . . . . . . . . . 01:10
. . . . . . . . . . </span>
. . . . . . . . . </span>
. . . . . . . . </span>
. . . . . . . </span>
. . . . . . </font>
. . . . . </font>
. . . . </span>
. . . </font>
. . </span>
. </p>
</div>

(line breaks and dots inserted by me.)

And here I see a couple of dangerous spots:

A) In the sequence of </b>,</font> and </span> the order should be reverse to the sequence of <b>, <font> and <span>. But the order does not match! By that the spans of bolded text or text with font attributes are not nested but overlap partially.

B) <spacer> is depreciated and should have a closing.

C) The two outer levels of markers are
<p> <spacer> … </p><p> … </p> <div>

Actual Results:
locate cursor ; press DEL key ; Writer hangs with full utilization of one core of my CPU.

Expected Results:
Do not hang.

Optional: have a tool to repair structure of document.


Reproducible: Always


User Profile Reset: No



Additional Info:
It did not use the OpenGL test program, because it wants to get 9,99$ per month.

I have the problem only with this document.