Comment 3 for bug 1698026

Probably a 4k display. The high display resolution is greater than the current themes (gtk2) can accommodate.

This issue may be addressed at the Paris hackfest at the end of the month, when gtk3 is considered.

https://inkscape.org/en/news/2017/06/06/hackfest-2017-paris/

Until an update is released, the best option is "larger". (Unless someone here has a workaround.)

TD