How to safely switch from vim-athena to vim-gtk?

Question

I have vim 7.4 Huge version with X11-Athena GUI installed on my laptop running ubuntu 16.04. I would like to safely switch to vim-gtk.

Do I have to uninstall existing vim installation and install vim-gtk from scratch, or is there a better way to achieve the same?

Update: I have installed vim-gtk3. Following are some additional information regarding my setup:

1. I have compiled vim from source, and vim --version returns the output appended below

VIM - Vi IMproved 7.4 (2013 Aug 10, compiled Jan 4 2016 01:01:13) Huge version with X11-Athena GUI. Features included (+) or not (-):
+arabic +file_in_path +mouse_sgr +tag_binary +autocmd +find_in_path -mouse_sysmouse +tag_old_static +balloon_eval +float +mouse_urxvt -tag_any_white +browse +folding +mouse_xterm -tcl ++builtin_terms -footer +multi_byte +terminfo +byte_offset +fork() +multi_lang +termresponse +cindent +gettext -mzscheme +textobjects +clientserver -hangul_input +netbeans_intg +title +clipboard +iconv +path_extra +toolbar +cmdline_compl +insert_expand -perl +user_commands +cmdline_hist +jumplist +persistent_undo +vertsplit +cmdline_info +keymap +postscript +virtualedit +comments +langmap +printer +visual +conceal +libcall +profile +visualextra +cryptv +linebreak +python +viminfo +cscope +lispindent -python3 +vreplace +cursorbind +listcmds +quickfix +wildignore +cursorshape +localmap +reltime +wildmenu +dialog_con_gui -lua +rightleft +windows +diff +menu -ruby +writebackup +digraphs +mksession +scrollbind +X11 -dnd +modify_fname +signs +xfontset -ebcdic +mouse +smartindent +xim +emacs_tags +mouseshape -sniff +xsmp_interact +eval +mouse_dec +startuptime +xterm_clipboard +ex_extra -mouse_gpm +statusline -xterm_save +extra_search -mouse_jsbterm -sun_workshop
+farsi +mouse_netterm +syntax
system vimrc file: "$VIM/vimrc" user vimrc file: "$HOME/.vimrc" 2nd user vimrc file: "~/.vim/vimrc" user exrc file: "$HOME/.exrc" system gvimrc file: "$VIM/gvimrc" user gvimrc file: "$HOME/.gvimrc" 2nd user gvimrc file: "~/.vim/gvimrc" system menu file: "$VIMRUNTIME/menu.vim" fall-back for $VIM: "/usr/local/share/vim" Compilation: gcc -c -I. -Iproto -DHAVE_CONFIG_H -DFEAT_GUI_ATHENA -I/usr/local/include -g -O2 -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=1
Linking: gcc -L/usr/local/lib -Wl,--as-needed -o vim -lXaw -lXmu -lXext -lXt -lSM -lICE -lXpm -lXt -lX11 -lXdmcp -lSM -lICE -ldl -lm -ltinfo -lnsl -ldl -L/usr/lib/python2.7 -lpython2.7

2. update-alternatives --display vim returns

vim - auto mode
link best version is /usr/bin/vim.gtk3
link currently points to /usr/bin/vim.gtk3
link vim is /usr/bin/vim
/usr/bin/vim.gtk3 - priority 50

3. update-alternatives --display gvim returns

   gvim - auto mode
   link best version is /usr/bin/vim.gtk3
   link currently points to /usr/bin/vim.gtk3
   link gvim is /usr/bin/gvim
   /usr/bin/vim.gtk3 - priority 50

gvim continues to launch vim in Athena gui.

Answer 1

You don't have to uninstall any of the existing packages. The vim-{athena,gtk,gtk3,nox} etc. packages just provide the Vim binary built with different feature sets and linked against different GUI toolkits.

1. Install the vim-gtk (or on newer systems vim-gtk3) package
2. Check whether the vim and gvim alternatives automatically switched to using /usr/bin/vim.gtk (or /usr/bin/vim.gtk3). Note: this should be the case if you haven't manually set priorities on the alternatives.
   1. $ update-alternatives --display vim
   2. If you want to change the alternative, run update-alternatives --config vim
   3. Repeat for gvim