[Writer] mouse doesn't touch scrollbar

I use:

LibreOffice Writer
Version: 6.1.5.2
Build ID: 6.1.5-2
CPU: 2; OS:Linux 4.20; UI render:default; VCL: gtk3_kde5;

On Plasma 5, when I want to scroll using mouse and I move mouse pointer to the edge of the monitor it doesn’t touch scrollbar - the space between monitor edge and scrollbar is to wide. See red dots on screenshot:

https://imgur.com/RwQyrtG

Is it possible to edit:

/etc/profile.d/libreoffice-still.sh

or

GTK2_RC_FILES=/usr/share/themes/QtCurve/gtk-2.0/gtkrc

to make scrollbars touch window edge?

Is it possible to apply qtcurve to Writer?

I tried:

GTK2_RC_FILES=/usr/share/themes/QtCurve/gtk-2.0/gtkrc libreoffice --writer

but it doesn’t change anything (whereas for other gtk program cherrytree it applies qtcurve scrollbar).

(edit: activated screenshot -AK)