The original maximum window size of 1920x1080 causes the window to not
fill the screen (and not even display all content) on large screens.
Removing the maximum window size makes the prompt display properly on
large screens.
Qt:KeepAspectRatio results in the background image becoming strangely
mangled. Changing to Qt::IgnoreAspectRatio results in scaling behavior
very similar to the behavior used by PCManFM-Qt by default when scaling
wallpapers, resulting in the image sometimes looking "stretched" or
"squished", but never mangled.
Aaron Rainbolt
Simon Quigley