Comment 9 for bug 448728

Fix committed in
  https://gitlab.com/inkscape/inkscape/commit/399b8e98c819d2f686a5176dd23393b183c660ec

The dialog should always have a usable (dynamically calculated) size now while also still being shrinkable down to the minimum size.

I'll also investigate if this can be back-ported to 0.92.x