Created attachment 189209 [details]
Test file used in the video

This is the file I used in the video. Use it to reproduce the bug.

However, the problem happens with any file.

@Jim, since you've been working with the Styles deck, do you have any idea why this is happening?

Reproducible.
Version: 24.2.0.0.alpha0+ (X86_64) / LibreOffice Community
Build ID: 33ae7c12bbdf19b76ced472ca8aed6cf66477bbe
CPU threads: 16; OS: Windows 10.0 Build 22621; UI render: Skia/Raster; VCL: win
Locale: es-ES (es_ES); UI: en-US Calc: CL threaded

(In reply to Rafael Lima from comment #2)
> @Jim, since you've been working with the Styles deck, do you have any idea
> why this is happening?
While looking for the cause of this happening I've found the cause of hair loss :-)

Probably not the correct solution to the problem but it does stop the jumping: 

IMPL_LINK_NOARG(StyleList, TimeOut, Timer*, void)
{
    if (!m_bDontUpdate)
    {
        m_bDontUpdate = true;
        if (!m_xTreeBox->get_visible())
            UpdateStyles(StyleFlags::UpdateFamilyList);
        else
        {
//            FillTreeBox(GetActualFamily());
//            SfxTemplateItem* pState = m_pFamilyState[m_nActFamily - 1].get();
//            if (pState)
//            {
//                m_pParentDialog->SelectStyle(pState->GetStyleName(), false, *this);
//                EnableDelete(nullptr);
//            }
        }
        m_bDontUpdate = false;
        pIdle.reset();
    }
    else
        pIdle->Start();
}

(In reply to Jim Raykowski from comment #4)
> Probably not the correct solution to the problem but it does stop the
> jumping: 

I confirm that commenting these lines in StyleList.cxx "fixes" the problem.

Now I don't know what would the consequence of removing these lines be... this seems to be a hack for some other problem (see a few lines above a comment about the use of this Timer).