After switching my desktop to FRUiT's Neon theme, every time I start LibreOffice I am blinded by the white splash screen and selection dialog, only to have to get used to the black page background. These png's solve the problem.
To install, first you must find LibreOffice's "program" folder. On my Arch system it is in /usr/lib/libreoffice/ but on PCLinuxOS it is in /opt/libreoffice/. The way I found it was searching / for intro.png. Then (after backing up the program folder) extract the downloaded tar file and write it into the program folder, overwriting the relevant png's.
These files would probably work with OpenOffice as well, but they might have to be renamed.