In the documentation I couldn't find a keybind to open and close a panel. Also is there a shortcut to reload a theme? If theme file is edited, I'd like to see changes without reopening 4coder.

There aren't default bindings for opening, closing panels and reloading the themes. If you have access to the custom layer you can add those, the functions are "close_panel", "open_panel_vsplit", "open_panel_hsplit" and "reload_themes".

You can also use the command lister to execute those commands. The default binding for the command lister is ALT + x.

Thanks.