small window & maximize button missing

When I create a Writer document from the Open Files/Remote Files/Recent File… screen, the window closes down to about 2/3rds of the screen, and the maximize button is not visible.

Please see Dropbox - bugs - Simplify your life

Build ID: 1:6.0.7-0ubuntu0.18.04.10
CPU threads: 4; OS: Linux 4.15; UI render: default; VCL: gtk3;
Locale: en-AU (en_AU.UTF-8); Calc: group

Dropbox file were removed.