There seems to be two ways to store preferences specific to gvim:
Keep an .vimrc file for vim and a .gvimrc file for gvim specific additions.
Keep all settings in .vimrc and wrap gvim specific settings in a feature detection conditional:
if has('gui_running')
" gvim specific settings here
endif
Given the existence of the latter option, why would I ever need a .gvimrc file?
When the GUI starts, some settings are reset and then .gvimrc is processed.
Consequently, if you want a non-default value for any of those settings, you'll need to set it in a .gvimrc; testing for GUI mode in .vimrc won't work.
One such setting is t_vb, the terminal code used for the visual bell; in fact, all terminal optionals are reset to defaults for GUI mode (see :help terminal-options).
Additionally a bunch of GUI setup and menu customization is carried out; if you want to tweak any of that, you'll want that in a .gvimrc or it may not have any impact.
Reading over :help gvimrc provides a good overview of things that may change on you between the sourcing of your .vimrc and .gvimrc that you may want to consider re-adjusting in the latter.
:gui command (within has("gui_running"), of course) to force the gui startup sequence to happen before any subsequent .vimrc commands. My .vimrc uses this to allow the default background light/dark setting to be set based on the actual GUI background color.
– Random832
Feb 27 '15 at 18:20
winposwhich changes the position of the window used by gvim. This has no effect (and makes no sense) within~/.vimrc, it has to be in~/.gvimrc– jalanb Feb 6 '15 at 0:02