Set more lines than maximum in GVim

Question

I want to set 58 lines. When I type

:set lines=58

it shrinks to 54 lines.

Answer 1

As Kent implied, the solution is to set guiheadroom to zero.

:set ghr=0

Answer 2

Maximum number of lines is determined by the size of your display / screen. Depending on font size you probably cannot fit 58 lines, therefore GVim automatically shrinks that value to 54. Try reducing your font size or increasing your display resolution (if you have that as an option).