I have installed vim-mode-plus package and added the following keymap bindings in the keymap.cson file.
'atom-text-editor.vim-mode-plus.normal-mode':
'ctrl-j': 'focus-pane-or-panel:focus-below'
'ctrl-k': 'focus-pane-or-panel:focus-above'
'ctrl-h': 'focus-pane-or-panel:focus-on-left'
however I am not able to switch between the panes ( I am on Windows)
I am able to switch if I use a built-in keybinding as below:
ctrl-w ctrl-j window:focus-pane-below Vim Mode Plus atom-text-editor.vim-mode-plus:not(.insert-mode)
Above is copied from the Keybindings search results in atom