window-resize-pixelwise

window-resize-pixelwise is a variable defined in `C source code'.
Its value is

nil

Documentation:
Non-nil means resize windows pixelwise.
This currently affects the functions: `split-window', `maximize-window',
`minimize-window', `fit-window-to-buffer' and `fit-frame-to-buffer', and
all functions that symmetrically resize a parent window.

Note that when a frame's pixel size is not a multiple of the
frame's character size, at least one window may get resized
pixelwise even if this option is nil.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 24.4 of Emacs.